phy: Add USB speed related PHY modes

Add following USB speed related PHY modes:
LS (Low Speed), FS (Full Speed), HS (High Speed), SS (Super Speed)

Speed related information is required by some QCOM PHY drivers
to program PHY monitor resume/remote-wakeup events in suspended
state. Speed is needed in order to set correct polarity of wakeup
events for detection. E.g. QUSB2 PHY monitors DP/DM line state
depending on whether speed is LS or FS/HS to detect resume.
Similarly QMP USB3 PHY in SS mode should monitor RX terminations
attach/detach and LFPS events depending on SSPHY is active or not.

Signed-off-by: Manu Gautam <mgautam@codeaurora.org>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>