Revisions between 2.10a and 2.50a (included) have
a known issue which may cause xHCI compliance tests
to fail and/or quality issues with Isochronous
transactions.

Note that this issue only impacts certain configurations
of those revisions, namely the ones which have clock
gating enabled.

The suggested workaround is to disable clock gating in
known broken revisions, make sure HW LPM is disabled
and set GCTL.SOFITPSYNC to 1.
Signed-off-by: Felipe Balbi <balbi@ti.com>