phy: phy-mtk-dp: make array driving_params static const

Don't populate the read-only array driving_params on the stack but instead
make it static const. Also makes the object code a little smaller.

Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Link: https://lore.kernel.org/r/20220929130147.97375-1-colin.i.king@gmail.com


Signed-off-by: Vinod Koul <vkoul@kernel.org>