iwlwifi: mei: fix W=1 warnings

There are a few warnings due to kernel-doc not understanding
the constructs the way they're done here, fix them.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/iwlwifi.20211219110000.1ef2bb24771c.I6a59ad2d64f719d3e27398951c8f1b678b0b1092@changeid