arch-arm: Downgrade constexpr causing build errors to const

Change-Id: Idf5ae62603b6181d44aaaef91b774fa7b26eb718
Signed-off-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/28167
Tested-by: kokoro <noreply+kokoro@google.com>
1 file changed