[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/platforms/Kconfig.cputype b/arch/powerpc/platforms/Kconfig.cputype
index 4c315be..3c7325e 100644
--- a/arch/powerpc/platforms/Kconfig.cputype
+++ b/arch/powerpc/platforms/Kconfig.cputype
@@ -37,6 +37,7 @@
 	select FSL_SOC
 	select 8xx
 	select WANT_DEVICE_TREE
+	select PPC_LIB_RHEAP
 
 config 40x
 	bool "AMCC 40x"