Implement the timer save restore as a direct translation of
the assembly code version.
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>

Implement the vgic-v3 save restore as a direct translation of
the assembly code version.
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>

Implement the vgic-v2 save restore (mostly) as a direct translation
of the assembly code version.
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>