clocksource / ACPI: Add probing infrastructure for ACPI-based clocksources

DT enjoys a rather nice probing infrastructure for clocksources,
while ACPI is so far stuck into a very distant past.

This patch introduces a declarative API, allowing clocksources
to be self-contained and be called when parsing the GTDT table.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Hanjun Guo <hanjun.guo@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index cd836cd..c4bd0e2 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -525,6 +525,7 @@
 	KERNEL_DTB()							\
 	IRQCHIP_OF_MATCH_TABLE()					\
 	ACPI_PROBE_TABLE(irqchip)					\
+	ACPI_PROBE_TABLE(clksrc)					\
 	EARLYCON_TABLE()						\
 	EARLYCON_OF_TABLES()