pinctrl: nexell: Cannot test unsigned to be negative

pinctrl: nexell: Cannot test unsigned to be negative

In s5pxx18_pinctrl_set_state testing count to be negative will always
fail as count is unsigned despite receiving the return value of a
function that returns an int. Change count and idx to be of type int to
allow the test to work as expected and remove the need for any implicit
casts. Also change pin to be u32 which is what all called functions
expect.

This issue was found by Smatch.

Signed-off-by: Andrew Goodbody <andrew.goodbody@linaro.org>