ARM: multi_v7_defconfig: remove one level of menu from Kconfig

remove menu "Broadcom Mobile SoC Selection"
This requires:
- selecting ARCH_BCM_MOBILE based on SoC selections
- fixup multi_v7_defconfig to work with new menu levels of mach-bcm.
Signed-off-by: Scott Branden <sbranden@broadcom.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

arch/arm/configs/multi_v7_defconfig

@@ -17,7 +17,8 @@ CONFIG_MACH_ARMADA_38X=y
 CONFIG_MACH_ARMADA_XP=y
 CONFIG_MACH_DOVE=y
 CONFIG_ARCH_BCM=y
-CONFIG_ARCH_BCM_MOBILE=y
+CONFIG_ARCH_BCM_21664=y
+CONFIG_ARCH_BCM_281XX=y
 CONFIG_ARCH_BCM_5301X=y
 CONFIG_ARCH_BRCMSTB=y
 CONFIG_ARCH_BERLIN=y