netfilter: nf_tables: add and use BE register load-store helpers

[ Upstream commit 7278b3c1 ]

Same as the existing ones, no conversions. This is just for sparse sake
only so that we no longer mix be16/u16 and be32/u32 types.

Alternative is to add __force __beX in various places, but this
seems nicer.

objdiff shows no changes.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Stable-dep-of: c301f098 ("netfilter: nf_tables: fix pointer math issue in nft_byteorder_eval()")
Signed-off-by: Sasha Levin <sashal@kernel.org>