Add bcm281xx architecture support code including a clock framework and
chip reset.  Define register block base addresses for the bcm281xx
architecture and create an empty gpio header file required when
CONFIG_CMD_GPIO is set.
Signed-off-by: NDarwin Rambo <drambo@broadcom.com>
Reviewed-by: NSteve Rae <srae@broadcom.com>
Reviewed-by: NTim Kryger <tkryger@linaro.org>