drm/bridge: tc358764: Use BIT() macro for actual bits

None of these four bits are bitfields, use BIT() macro and treat
them as bits. No functional change.

Signed-off-by: Marek Vasut <marex@denx.de>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Robert Foss <rfoss@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20230615201635.565973-1-marex@denx.de