phy: General struct and field cleanup

Move MSM8996 specific PHY vreg list struct name to a genernal one as it is
used by all PHYs. Add a specific field to handle dual lane situation.

Signed-off-by: Can Guo <cang@codeaurora.org>
Reviewed-by: Evan Green <evgreen@chromium.org>
Reviewed-by: Manu Gautam <mgautam@codeaurora.org>
Reviewed-by: Vivek Gautam <vivek.gautam@codeaurora.org>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>