soc: mediatek: pwrap: fix compiler errors

[ Upstream commit fb2c1934f30577756e55e24e8870b45c78da3bc2 ]

When compiling using sparse, we got the following error:
drivers/soc/mediatek/mtk-pmic-wrap.c:686:25: error: dubious one-bit signed bitfield

Changing the data type to unsigned fixes this.

Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>