pinctrl: samsung: Do not initialise statics to 0

Static variables are initialised to 0 by GCC.
Fixes the following checkpatch error:
ERROR: do not initialise statics to 0 or NULL
FILE: pinctrl/pinctrl-samsung.c:50:
static unsigned int pin_base = 0;

Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>