rtc: tps65910: use 'unsigned int' instead of 'unsigned' in arguments

Fixes checkpatch.pl warning:
WARNING: Prefer 'unsigned int' to bare use of 'unsigned'

Signed-off-by: Vesa Jääskeläinen <vesa.jaaskelainen@vaisala.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>