iwlwifi: mvm: move iwl_mvm_stop_device() out of line

This function has grown quite a bit over time, move it
out of line before we grow it even further.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Link: https://lore.kernel.org/r/iwlwifi.20201209231352.1a0211e66906.I572eb69dc3738319310c9cbe03a36d942f4f68f7@changeid


Signed-off-by: Luca Coelho <luciano.coelho@intel.com>