powerpc: Add POWER8 CPU selection

This allows the user to build a kernel targeted at POWER8
(ie gcc -mcpu=power8).
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/Makefile

@@ -135,6 +135,7 @@ CFLAGS-$(CONFIG_POWER4_CPU) += $(call cc-option,-mcpu=power4)
 CFLAGS-$(CONFIG_POWER5_CPU) += $(call cc-option,-mcpu=power5)
 CFLAGS-$(CONFIG_POWER6_CPU) += $(call cc-option,-mcpu=power6)
 CFLAGS-$(CONFIG_POWER7_CPU) += $(call cc-option,-mcpu=power7)
+CFLAGS-$(CONFIG_POWER8_CPU) += $(call cc-option,-mcpu=power8)
 
 # Altivec option not allowed with e500mc64 in GCC.
 ifeq ($(CONFIG_ALTIVEC),y)

arch/powerpc/platforms/Kconfig.cputype

@@ -117,6 +117,10 @@ config POWER7_CPU
 	bool "POWER7"
 	depends on PPC_BOOK3S_64
 
+config POWER8_CPU
+	bool "POWER8"
+	depends on PPC_BOOK3S_64
+
 config E5500_CPU
 	bool "Freescale e5500"
 	depends on E500