alpha: Convert htog and gtoh to htole and letoh.

alpha: Convert htog and gtoh to htole and letoh.

When within the Alpha arch, we know the guest endianness already.

Change-Id: Iee22a33451a06c6e6a5c7d1e8c71f0b00e98ae3f
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/22367
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-by: Brandon Potter <Brandon.Potter@amd.com>
Maintainer: Gabe Black <gabeblack@google.com>