phy: ti-pipe3: introduce local struct device* in probe

No functional change. Introduce local struct device pointer in
probe and replace using &pdev->dev/phy->dev with the local
device pointer. This is in preparation to split ti_pipe3_probe
and add separate functions for getting mem resource, getting
sysctrl and getting clocks.

Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>