arch-arm: Rewrite the TLB flushing interface

arch-arm: Rewrite the TLB flushing interface

We are now using an overloaded flush method which has
different TLBI ops as arguments.

This is simplifying the interface and it is allowing us to
encode some state in the TLBIOp which will then be passed
to the TLB. This is a step towards making the TLB a stateless
cache of translations

Change-Id: Ic4fbae72dc3cfe756047148b1cf5f144298c8b08
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/35240
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-by: Richard Cooper <richard.cooper@arm.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>