powerpc: Pull out MPC106 (grackle) initialization code into its own file

This is so that the 32-bit CHRP code can use it.  The MPC106
initialization code is now in arch/powerpc/sysdev/grackle.c and
is controlled by CONFIG_PPC_MPC106.

Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index ce5100c..964ded4 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -286,6 +286,7 @@
 	select PPC_I8259
 	select PPC_INDIRECT_PCI
 	select PPC_RTAS
+	select PPC_MPC106
 	default y
 
 config PPC_PMAC
@@ -366,6 +367,10 @@
 	bool
 	default y
 
+config PPC_MPC106
+	bool
+	default n
+
 source "drivers/cpufreq/Kconfig"
 
 config CPU_FREQ_PMAC