usb: xhci: Reduce the BESL value to improve L1 residency

BESL value decides the L1 LPM resume latency and hence
controls the L1 suspend residency. Lower BESL values have
significant improvement in L1 residency for 1ms SI which
results in more power savings. Set this value to 0 to
achieve this saving.

Change-Id: If3df0424c273ed68b7e070c922f5757381114ca4
Signed-off-by: Elson Roy Serrao <eserrao@codeaurora.org>