soc: renesas: Rework Kconfig and Makefile logic

The goals are to:
  - Allow precise control over and automatic selection of which
    (sub)drivers are used for which SoC,
  - Allow adding support for new SoCs easily,
  - Allow compile-testing of all (sub)drivers,
  - Keep driver selection logic in the subsystem-specific Kconfig,
    independent from the architecture-specific Kconfig (i.e. no "select"
    from arch/arm64/Kconfig.platforms), to avoid dependencies.

This is implemented by:
  - Introducing Kconfig symbols for all drivers and sub-drivers,
  - Introducing the Kconfig symbol SOC_RENESAS, which is enabled
    automatically when building for a Renesas ARM platform, and which
    enables all required drivers without interaction of the user, based
    on SoC-specific ARCH_* symbols,
  - Allowing the user to enable any Kconfig symbol manually if
    COMPILE_TEST is enabled,
  - Using the new Kconfig symbols instead of the ARCH_* symbols to
    control compilation in the Makefile,
  - Always entering drivers/soc/renesas/ during the build.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
diff --git a/drivers/soc/renesas/rcar-sysc.c b/drivers/soc/renesas/rcar-sysc.c
index 225c35c..4d0125d 100644
--- a/drivers/soc/renesas/rcar-sysc.c
+++ b/drivers/soc/renesas/rcar-sysc.c
@@ -275,35 +275,33 @@ static void __init rcar_sysc_pd_setup(struct rcar_sysc_pd *pd)
 }
 
 static const struct of_device_id rcar_sysc_matches[] = {
-#ifdef CONFIG_ARCH_R8A7743
+#ifdef CONFIG_SYSC_R8A7743
 	{ .compatible = "renesas,r8a7743-sysc", .data = &r8a7743_sysc_info },
 #endif
-#ifdef CONFIG_ARCH_R8A7745
+#ifdef CONFIG_SYSC_R8A7745
 	{ .compatible = "renesas,r8a7745-sysc", .data = &r8a7745_sysc_info },
 #endif
-#ifdef CONFIG_ARCH_R8A7779
+#ifdef CONFIG_SYSC_R8A7779
 	{ .compatible = "renesas,r8a7779-sysc", .data = &r8a7779_sysc_info },
 #endif
-#ifdef CONFIG_ARCH_R8A7790
+#ifdef CONFIG_SYSC_R8A7790
 	{ .compatible = "renesas,r8a7790-sysc", .data = &r8a7790_sysc_info },
 #endif
-#ifdef CONFIG_ARCH_R8A7791
+#ifdef CONFIG_SYSC_R8A7791
 	{ .compatible = "renesas,r8a7791-sysc", .data = &r8a7791_sysc_info },
-#endif
-#ifdef CONFIG_ARCH_R8A7792
-	{ .compatible = "renesas,r8a7792-sysc", .data = &r8a7792_sysc_info },
-#endif
-#ifdef CONFIG_ARCH_R8A7793
 	/* R-Car M2-N is identical to R-Car M2-W w.r.t. power domains. */
 	{ .compatible = "renesas,r8a7793-sysc", .data = &r8a7791_sysc_info },
 #endif
-#ifdef CONFIG_ARCH_R8A7794
+#ifdef CONFIG_SYSC_R8A7792
+	{ .compatible = "renesas,r8a7792-sysc", .data = &r8a7792_sysc_info },
+#endif
+#ifdef CONFIG_SYSC_R8A7794
 	{ .compatible = "renesas,r8a7794-sysc", .data = &r8a7794_sysc_info },
 #endif
-#ifdef CONFIG_ARCH_R8A7795
+#ifdef CONFIG_SYSC_R8A7795
 	{ .compatible = "renesas,r8a7795-sysc", .data = &r8a7795_sysc_info },
 #endif
-#ifdef CONFIG_ARCH_R8A7796
+#ifdef CONFIG_SYSC_R8A7796
 	{ .compatible = "renesas,r8a7796-sysc", .data = &r8a7796_sysc_info },
 #endif
 	{ /* sentinel */ }