phy: tegra: p2u: Set ENABLE_L2_EXIT_RATE_CHANGE in calibration

Set ENABLE_L2_EXIT_RATE_CHANGE register bit to request UPHY PLL rate change
to Gen1 during initialization. This helps in the below surprise link down
cases,
  - Surprise link down happens at Gen3/Gen4 link speed.
  - Surprise link down happens and external REFCLK is cut off, which causes
UPHY PLL rate to deviate to an invalid rate.

Signed-off-by: Vidya Sagar <vidyas@nvidia.com>
Link: https://lore.kernel.org/r/20221013183854.21087-9-vidyas@nvidia.com


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