phy: allwinner: phy-sun6i-mipi-dphy: Make RX support optional

phy: allwinner: phy-sun6i-mipi-dphy: Make RX support optional

While all variants of the DPHY likely support RX mode, the new variant
in the A100 is not used in this direction by the BSP, and it has some
analog register changes, so its RX power-on sequence is unknown. To be
safe, limit RX support to variants where the power-on sequence is known.

Signed-off-by: Samuel Holland <samuel@sholland.org>
Link: https://lore.kernel.org/r/20221114022113.31694-6-samuel@sholland.org
Signed-off-by: Vinod Koul <vkoul@kernel.org>