crypto: arm64/gcm - use inline helper to suppress indirect calls

Introduce an inline wrapper for ghash_do_update() that incorporates
the indirect call to the asm routine that is passed as an argument,
and keep the non-SIMD fallback code out of line. This ensures that
all references to the function pointer are inlined where the address
is taken, removing the need for any indirect calls to begin with.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>