KVM: arm64: gic-v3: Switch vGIC-v3 to use generated ICH_VMCR_EL2

KVM: arm64: gic-v3: Switch vGIC-v3 to use generated ICH_VMCR_EL2

The VGIC-v3 code relied on hand-written definitions for the
ICH_VMCR_EL2 register. This register, and the associated fields, is
now generated as part of the sysreg framework. Move to using the
generated definitions instead of the hand-written ones.

There are no functional changes as part of this change.

Signed-off-by: Sascha Bischoff <sascha.bischoff@arm.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Link: https://patch.msgid.link/20260128175919.3828384-3-sascha.bischoff@arm.com
Signed-off-by: Marc Zyngier <maz@kernel.org>