staging: regulator: hi6421v600-regulator: fix some coding style issues

Fix the remaining issues complained by checkpatch.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/af5101fa2ab1d267ac5ac22603f95c6065ac110f.1597647359.git.mchehab+huawei@kernel.org


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>