usb: host: xhci: Move LPM support quirk to xhci_plat_quirks

xhci quirks is initialized in xhci_gen_setup() which gets called
from usb_add_hcd(). Since LPM support quirk is ORed to xhci quirk
before calling usb_add_hcd(), quirk gets overwritten. Fix this issue
by moving LPM support quirk to xhci_plat_quirks() which gets called
after xhci quirk is initialized.

Change-Id: I8fb4684d434f098408dddb636b5482cb65b6999a
Signed-off-by: Hemant Kumar <hemantk@codeaurora.org>