regmap: Prefer unsigned int to bare use of unsigned

Fix checkpatch warnings:
    WARNING: Prefer 'unsigned int' to bare use of 'unsigned'

Signed-off-by: Jinchao Wang <wjc@cdjrlc.com>
Link: https://lore.kernel.org/r/20210628171907.63646-1-wjc@cdjrlc.com


Signed-off-by: Mark Brown <broonie@kernel.org>