usb: gadget: composite: enable BESL support

commit a6615937bcd9234e6d6bb817c3701fce44d0a84d upstream.

According to USB 2.0 ECN Errata for Link Power
Management (USB2-LPM-Errata-final.pdf), BESL
must be enabled if LPM is enabled.

This helps with USB30CV TD 9.21 LPM L1
Suspend Resume Test.

Signed-off-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Du, Changbin <changbin.du@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>