crypto: marvell - remove set but not used variable 'index'
Fixes gcc '-Wunused-but-set-variable' warning:
drivers/crypto/marvell/hash.c: In function 'mv_cesa_ahash_pad_req':
drivers/crypto/marvell/hash.c:138:15: warning: variable 'index' set but not used [-Wunused-but-set-variable]