soc: mediatek: pwrap: use BIT() macro

Use a better BIT() marco for the bit definition.
No functional changes, cleanup only.

Signed-off-by: Hsin-Hsiung Wang <hsin-hsiung.wang@mediatek.com>
Reviewed-by: Nicolas Boichat <drinkcat@chromium.org>
Link: https://lore.kernel.org/r/1615563286-22126-2-git-send-email-hsin-hsiung.wang@mediatek.com


Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>