target/arm: Move some functions used only in translate-neon.inc.c to that file

target/arm: Move some functions used only in translate-neon.inc.c to that file

The functions neon_element_offset(), neon_load_element(),
neon_load_element64(), neon_store_element() and
neon_store_element64() are used only in the translate-neon.inc.c
file, so move their definitions there.

Since the .inc.c file is #included in translate.c this doesn't make
much difference currently, but it's a more logical place to put the
functions and it might be helpful if we ever decide to try to make
the .inc.c files genuinely separate compilation units.

Signed-off-by: Peter Maydell <[email protected]>
Reviewed-by: Richard Henderson <[email protected]>
Message-id: 20200616170844[email protected]