phy: ti: j721e-wiz: Configure 'p_standard_mode' only for DP/QSGMII

Configure 'p_standard_mode' only for DP/QSGMII as for other modes
it's not used as per the programming sequence. Add "continue" in the
else to prevent random value from being written to p_standard_mode.

Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Link: https://lore.kernel.org/r/20210331131417.15596-1-kishon@ti.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>