powerpc: Add module autoloading based on CPU features

This patch provides the necessary infrastructure to allow drivers
to be automatically loaded via udev. It implements the minimum
required to be able to use module_cpu_feature_match() to trigger
the GENERIC_CPU_AUTOPROBE mechanisms.

The features exposed are a mirror of the cpu_user_features
(converted to an offset from a mask). This decision was made to
ensure that the behavior between features for module loading and
userspace are consistent.

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
[mpe: Only define the bits we currently need]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 9b6d36b..a5e0b47 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -165,6 +165,7 @@
 	select ARCH_HAS_UBSAN_SANITIZE_ALL
 	select ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT
 	select HAVE_LIVEPATCH if HAVE_DYNAMIC_FTRACE_WITH_REGS
+	select GENERIC_CPU_AUTOPROBE
 
 config GENERIC_CSUM
 	def_bool CPU_LITTLE_ENDIAN