KVM: arm64: Map AArch32 cp15 register to AArch64 sysregs

Move all the cp15 registers over to their AArch64 counterpart.
This requires the annotation of a few of them (such as the usual
DFAR/IFAR vs FAR_EL1), and a new helper that generates mask/shift
pairs for the various configurations.

Signed-off-by: Marc Zyngier <maz@kernel.org>