crypto: vmx - drop unexpected word 'for' in comments

there is an unexpected word 'for' in the comments that need to be dropped

file - drivers/crypto/vmx/ghashp8-ppc.pl
line - 19

"# GHASH for for PowerISA v2.07."

changed to:

"# GHASH for PowerISA v2.07."

Signed-off-by: Jiang Jian <jiangjian@cdjrlc.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>