arch-arm: Remove MISCREG commented numbers

arch-arm: Remove MISCREG commented numbers

Having an enum number might be useful in case we wanted to know how many
miscregs we have, but on the other hand it makes it tedious to update
the register list, since every commented number must be bumped.  This
patch is removing the comments holding the MISCREG numbers

Change-Id: Ic5aba93885e4b8d6cb3bd6a4c49900b9e5474276
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/13996
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>