KVM: arm64: nv: Accelerate EL0 timer read accesses when FEAT_ECV in use

KVM: arm64: nv: Accelerate EL0 timer read accesses when FEAT_ECV in use

Although FEAT_ECV allows us to correctly emulate the timers, it also
reduces performances pretty badly.

Mitigate this by emulating the CTL/CVAL register reads in the
inner run loop, without returning to the general kernel.

Acked-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20241217142321.763801-6-maz@kernel.org
Signed-off-by: Marc Zyngier <maz@kernel.org>