usb: phy: qmp: Add support for QMP phy_phy reset

On some SOCs there is a new reset signal phy_phy_reset
which replaces the reset functionality of the pipe_clk.
Add support for this by adding it as an optional clock
and use it if present.

Change-Id: I7275b7b39c20224911be3b713d567328c16da3f1
Signed-off-by: Mayank Rana <mrana@codeaurora.org>