[POWERPC] rheap: Changes config mechanism

Instead of having in the makefile all the option that
requires rheap, we define a configuration symbol
and when needed we make sure it's selected.

Signed-off-by: Sylvain Munaut <tnt@246tNt.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 037664d..8300e6a 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -698,3 +698,7 @@
 config PPC_CLOCK
 	bool
 	default n
+
+config PPC_LIB_RHEAP
+	bool
+