iwlwifi: pcie: clean up some rx code

iwlwifi: pcie: clean up some rx code

We don't need the sequence/index/cmd_index unless we're doing
reclaim, they're not even valid in the other cases. Move the
variables and their assignments into the right if statement
and combine the two if statements into a single one as well.

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.20201209231352.6207fdcc91a9.Ia71e766ead7560262f4bc6ad3da6f1117c498cd6@changeid
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>