target/arm: Split vfp_access_check() into A and M versions

target/arm: Split vfp_access_check() into A and M versions

vfp_access_check and its helper routine full_vfp_access_check() has
gradually grown and is now an awkward mix of A-profile only and
M-profile only pieces.  Refactor it into an A-profile only and an
M-profile only version, taking advantage of the fact that now the
only direct call to full_vfp_access_check() is in A-profile-only
code.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20210618141019.10671-7-peter.maydell@linaro.org