Further troubleshooting was unable to narrow the problem down. So we
don't have much choice other than to block WFI when the EMAC is active
with the HWMOD_BLOCK_WFI flag.
Based on Mark's original patch. We're removing the omap_device-based
pm_lats code, so a different approach was needed.
This third version contains some corrections thanks to Mark's review.
Signed-off-by: Paul Walmsley <paul@pwsan.com> Cc: Mark A. Greer <mgreer@animalcreek.com> Acked-by: Mark A. Greer <mgreer@animalcreek.com>