ARM: 5954/1: ep93xx: move gpio interrupt support to gpio.c

ARM: 5954/1: ep93xx: move gpio interrupt support to gpio.c

The GPIO support in core.c handles the interrupt support for GPIO
ports A, B, and F. The gpiolib implementation in gpio.c needs to
access the function ep93xx_gpio_int_mask when a gpio pin is made
an output and ep93xx_gpio_update_int_params in order to update
the registers.

Moving this support from core.c to gpio.c allows making the two
functions static. It also keeps all the GPIO handling together in one
file.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Acked-by: Ryan Mallon <ryan@bluewatersys.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>