phy: cadence: Sierra: Fix offset of DEQ open eye algorithm control register

phy: cadence: Sierra: Fix offset of DEQ open eye algorithm control register

Fix the value of SIERRA_DEQ_OPENEYE_CTRL_PREG and add a definition for
SIERRA_DEQ_TAU_EPIOFFSET_MODE_PREG. This fixes the SGMII single link
register configuration.

Fixes: 7a5ad9b4b98c ("phy: cadence: Sierra: Update single link PCIe register configuration")
Signed-off-by: Bartosz Wawrzyniak <bwawrzyn@cisco.com>
Link: https://lore.kernel.org/r/20241003123405.1101157-1-bwawrzyn@cisco.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>