phy: tegra: xusb: Add wake/sleepwalk for Tegra210

This commit implements Tegra210 XUSB PADCTL wake and sleepwalk
routines. Sleepwalk logic is in PMC (always-on) hardware block.
PMC driver provides managed access to the sleepwalk registers
via regmap framework.

Signed-off-by: JC Kuo <[email protected]>
Acked-By: Vinod Koul <[email protected]>
Signed-off-by: Thierry Reding <[email protected]>

Author: jckuo