powerpc: Add self-tests of the feature fixup code

This commit adds tests of the feature fixup code, they are run during
boot if CONFIG_FTR_FIXUP_SELFTEST=y. Some of the tests manually invoke
the patching routines to check their behaviour, and others use the
macros and so are patched during the normal patching done during boot.

Because we have two sets of macros with different names, we use a macro
to generate the test of the macros, very niiiice.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/arch/powerpc/Kconfig.debug b/arch/powerpc/Kconfig.debug
index dc58939..2840ab6 100644
--- a/arch/powerpc/Kconfig.debug
+++ b/arch/powerpc/Kconfig.debug
@@ -62,6 +62,11 @@
 	depends on DEBUG_KERNEL
 	default n
 
+config FTR_FIXUP_SELFTEST
+	bool "Run self-tests of the feature-fixup code."
+	depends on DEBUG_KERNEL
+	default n
+
 choice
 	prompt "Serial Port"
 	depends on KGDB