arch-arm: Add destRegIdxArr arrays to TME instructions

arch-arm: Add destRegIdxArr arrays to TME instructions

This is needed as the base StaticInst class is no longer holding the
index array and it is up to the derived class to allocate the
storage depending on the number of registers used

Change-Id: I389e39a7e09d31f370d63a6e61fe6ee3faaac7db
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/40375
Reviewed-by: Gabe Black <gabe.black@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>