crypto: gcm - simplify error handling in crypto_rfc4543_create()

crypto: gcm - simplify error handling in crypto_rfc4543_create()

Simplify the error handling in crypto_rfc4543_create() by taking
advantage of crypto_grab_aead() now handling an ERR_PTR() name and by
taking advantage of crypto_drop_aead() now accepting (as a no-op) a
spawn that hasn't been grabbed yet.

Conveniently, this eliminates the 'ccm_name' variable which was
incorrectly named (it should have been 'gcm_name').

Also fix a weird case where a line was terminated by a comma rather than
a semicolon, causing the statement to be continued on the next line.
Fortunately the code still behaved as intended, though.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>