phy: ti: j721e-wiz: Configure full rate divider for AM64

The frequency of the txmclk between PCIe and SERDES has
changed to 250MHz from 500MHz. Configure full rate divider
for AM64 accordingly.

Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Link: https://lore.kernel.org/r/20210310120840.16447-4-kishon@ti.com


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