[POWERPC] Generic DCR infrastructure

This patch adds new dcr_map/dcr_read/dcr_write accessors for DCRs that
can be used by drivers to transparently address either native DCRs or
memory mapped DCRs. The implementation for memory mapped DCRs is done
after the binding being currently worked on for SLOF and the Axon
chipset. This patch enables it for the cell native platform

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/arch/ppc/Kconfig b/arch/ppc/Kconfig
index ef018e2..edf71a4 100644
--- a/arch/ppc/Kconfig
+++ b/arch/ppc/Kconfig
@@ -77,9 +77,11 @@
 
 config 40x
 	bool "40x"
+	select PPC_DCR_NATIVE
 
 config 44x
 	bool "44x"
+	select PPC_DCR_NATIVE
 
 config 8xx
 	bool "8xx"
@@ -95,6 +97,15 @@
 config PPC_FPU
 	bool
 
+config PPC_DCR_NATIVE
+	bool
+	default n
+
+config PPC_DCR
+	bool
+	depends on PPC_DCR_NATIVE
+	default y
+
 config BOOKE
 	bool
 	depends on E200 || E500