crypto: chelsio - Make function aead_ccm_validate_input static

Function aead_ccm_validate_input is local to the source and does not
need to be in global scope, so make it static.

Cleans up sparse warning:
drivers/crypto/chelsio/chcr_algo.c:2627:5: warning: symbol
'aead_ccm_validate_input' was not declared. Should it be static?

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>