KVM: arm64: Restore TCR2_EL1 register visibility to userspace

Upstream Status: RHEL only
JIRA: https://issues.redhat.com/browse/RHEL-89567

Commit f1ca81f ("[PATCH v2 2/3] KVM: arm64: Hide TCR2_EL1 from
userspace when disabled for guests") broke the migration because it
suddently hides TCR2_EL1 register to userspace. Let's remove the
visibility callback setting  to restore the previous behavior. We
don't do a full revert becasue the trap setup and el2 visibility
changes are still sensible from guest point of view.

Signed-off-by: Eric Auger <eric.auger@redhat.com>

Author: eauger

arch/arm64/kvm/sys_regs.c

@@ -2695,8 +2695,7 @@ static const struct sys_reg_desc sys_reg_descs[] = {
 	{ SYS_DESC(SYS_TTBR0_EL1), access_vm_reg, reset_unknown, TTBR0_EL1 },
 	{ SYS_DESC(SYS_TTBR1_EL1), access_vm_reg, reset_unknown, TTBR1_EL1 },
 	{ SYS_DESC(SYS_TCR_EL1), access_vm_reg, reset_val, TCR_EL1, 0 },
-	{ SYS_DESC(SYS_TCR2_EL1), access_vm_reg, reset_val, TCR2_EL1, 0,
-	  .visibility = tcr2_visibility },
+	{ SYS_DESC(SYS_TCR2_EL1), access_vm_reg, reset_val, TCR2_EL1, 0 },
 
 	PTRAUTH_KEY(APIA),
 	PTRAUTH_KEY(APIB),