staging: mt7621-gpio: prefer unsigned int to bare unsigned

This commit replaces some bare unsigned definitions in some
function parameters in favour of 'unsigned int' which is
preferred.

This also fix checkpatch warnings about this.

Signed-off-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
Reviewed-by: NeilBrown <neil@brown.name>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>