xlat: Introduce function xlat_arch_tlbi_va_regime()

Introduce a variant of the TLB invalidation helper function that
allows the targeted translation regime to be specified, rather than
defaulting to the current one.

This new function is useful in the context of EL3 software managing
translation tables for the S-EL1&0 translation regime, as then it
might need to invalidate S-EL1&0 TLB entries rather than EL3 ones.

Define a new enumeration to be able to represent translation regimes in
the xlat tables library.

Change-Id: Ibe4438dbea2d7a6e7470bfb68ff805d8bf6b07e5
Co-authored-by: Sandrine Bailleux <sandrine.bailleux@arm.com>
Co-authored-by: Douglas Raillard <douglas.raillard@arm.com>
Co-authored-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>