pinctrl: sirf: remove sirfsoc_gpio_set_pull function

The prima2 platform advertises needing no mach/gpio.h header file,
but its pinctrl driver now has a sirfsoc_gpio_set_pull function
that uses constants defined in arch/arm/mach-prima2/include/mach/gpio.h,
which fails to build.

Fortunately, the sirfsoc_gpio_set_pull is not used anywhere in the
kernel, so we can safely remove it. Any out of tree drivers using
it will have to be converted to use proper pinctrl functions to
do the same.

Without this patch, building prima2_defconfig results in:

drivers/pinctrl/pinctrl-sirf.c: In function 'sirfsoc_gpio_set_pull':
drivers/pinctrl/pinctrl-sirf.c:1331:7: error: 'SIRFSOC_GPIO_PULL_NONE' undeclared (first use in this function)
drivers/pinctrl/pinctrl-sirf.c:1331:7: note: each undeclared identifier is reported only once for each function it appears in
drivers/pinctrl/pinctrl-sirf.c:1334:7: error: 'SIRFSOC_GPIO_PULL_UP' undeclared (first use in this function)
drivers/pinctrl/pinctrl-sirf.c:1338:7: error: 'SIRFSOC_GPIO_PULL_DOWN' undeclared (first use in this function)

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Barry Song <Baohua.Song@csr.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>