phy: rockchip-inno-usb2: correct 480m output clock stable time.

phy: rockchip-inno-usb2: correct 480m output clock stable time.

We found that the system on rk3366 SoC was crashed due to 480m
output clock of usb-phy was unstable after clock had been enabled by
gpu module.

Theoretically, 1 millisecond is a critical value for 480 output clock
stable time, so we try changing the delay time to 1.2 millisecond to
avoid this issue.

Change-Id: I8790eb3d7fccc9fbaa7b49f8d4386df147a95b75
Signed-off-by: Frank Wang <frank.wang@rock-chips.com>