xHCI: BESL calculation based on USB2.0 LPM errata

The latest released errata for USB2.0 ECN LPM adds new fields to USB2.0
extension descriptor, defines two BESL values for device: baseline BESL
and deep BESL. Baseline BESL value communicates a nominal power savings
design point and the deep BESL value communicates a significant power
savings design point.

If device indicates BESL value, driver will use a value count in both
host BESL and device BESL. Use baseline BESL value as default.

Signed-off-by: Andiry Xu <andiry.xu@amd.com>
Tested-by: Jason Fan <jcfan@qca.qualcomm.com>
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>