mac80111: aes_ccm: cleanup ieee80211_aes_key_setup_encrypt()

This code is written using an anti-pattern called "success handling"
which makes it hard to read, especially if you are used to normal kernel
style.  It should instead be written as a list of directives in a row
with branches for error handling.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>