usb: dwc2: Add core parameters for LPM support

Add lpm, lpm_clock_gating, besl, hird_threshold_en and hird_threshold
core parameters. These will indicate LPM and LPM Errata support
as well as chosen L1 sleeping mode for the core and PHY.

Signed-off-by: Sevak Arakelyan <sevaka@synopsys.com>
Signed-off-by: Grigor Tovmasyan <tovmasya@synopsys.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>