target/arm: Implement MTE tag-checking functions for FEAT_MOPS

target/arm: Implement MTE tag-checking functions for FEAT_MOPS

The FEAT_MOPS instructions need a couple of helper routines that
check for MTE tag failures:
 * mte_mops_probe() checks whether there is going to be a tag
   error in the next up-to-a-page worth of data
 * mte_check_fail() is an existing function to record the fact
   of a tag failure, which we need to make global so we can
   call it from helper-a64.c

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20230912140434.1333369-7-peter.maydell@linaro.org