usb: phy: qmp: Use clk_round_rate on aux_clk

On MSM8994 aux_clk supports 1.2MHz not 1.0Mhz. To simplify
having to know exactly what frequency to use, call clk_round_rate()
to get the maximum supported frequency to pass to clk_set_rate().

Change-Id: I954d36fc3dfeea3facea6b1523936b6c620627e8
Signed-off-by: Jack Pham <jackp@codeaurora.org>