If keyguard has preferred refresh rate, always use it

Even if we're dozing b/c this # is ignored in low-power mode,
but we still want the display to already be at this refresh
rate when we exit doze.

Test: on device w/ udfps enrolled + preferred refresh rate config,
check dumpsys display when in AOD and check for refresh rate vote
(ie: PRIORITY_APP_REQUEST_REFRESH_RATE_RANGE = preferred rate)
Bug: 192699858
Change-Id: I9ae31e64c4d698eb9e7da46fad5331632b632090