Bluetooth: btbcm: Move request/release_firmware()

Move request/release_firmware() out of btbcm_patchram().
This allows a better error management, if request_firmware() returns an
error then the controller will be used without firmware loading and 0 is
returned.
This will imply to change btbcm_patchram() to accept a firmware instead
of firmware name.

Signed-off-by: Frederic Danis <frederic.danis@linux.intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>