pinctrl: exynos: Reduce variables scope

Pull some variables declared in exynos_pinctrl_set_state() into its
loop, to reduce their scope. Style commit, no functional change.

Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org>
Signed-off-by: Minkyu Kang <mk7.kang@samsung.com>