Rename __tlb_switch_to_{guest,host}() to
{enter,exit}_vmid_context() in VHE code to maintain symmetry
between the nVHE and VHE TLB invalidations.

No functional change intended.
Suggested-by: Oliver Upton <oliver.upton@linux.dev>
Signed-off-by: Fuad Tabba <tabba@google.com>
Acked-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20240423150538.2103045-11-tabba@google.comSigned-off-by: Marc Zyngier <maz@kernel.org>