brcmfmac: Prevent re-tuning conflicting with 'wake-up'

brcmfmac: Prevent re-tuning conflicting with 'wake-up'

If the device is in a custom sleep state, then re-tuning
will fail. Add calls to sdio_retune_hold_now() and
sdio_retune_release() to prevent re-tuning before the
wake-up command. In the case re-tuning was needed, the
wake-up command might return an error, but the wake-up
is expected still to have happened, and the error is
anyway ignored.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>