ARM: nomadik: hide MACH_NOMADIK_8815NHK in Kconfig

The nomadik multiplatform support made it possible to select
MACH_NOMADIK_8815NHK without selecting ARCH_NOMADIK, which leads
to build errors when we also select ARMv6/v7 targets. Adding the
ifdef here restores the intended behavior.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

arch/arm/mach-nomadik/Kconfig

@@ -17,6 +17,7 @@ config ARCH_NOMADIK
 	help
 	  Support for the Nomadik platform by ST-Ericsson
 
+if ARCH_NOMADIK
 menu "Nomadik boards"
 
 config MACH_NOMADIK_8815NHK
@@ -26,6 +27,7 @@ config MACH_NOMADIK_8815NHK
 	select I2C_ALGOBIT
 
 endmenu
+endif
 
 config NOMADIK_8815
 	depends on ARCH_NOMADIK