pinctrl: bcm: Allow PINCTRL_BCM2835 for ARCH_BRCMSTB

ARCH_BRCMSTB needs to use the BCM2835 pin controller for chips
like BCM7211 which adopted that pin controller for GPIO. This
commit makes the option menu configurable with default enabled
for ARCH_BRCMSTB and ARCH_BCM2835.

Signed-off-by: Doug Berger <opendmb@gmail.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>