KVM: arm64: Add missing hyp_enter when trapping sysreg

KVM: arm64: Add missing hyp_enter when trapping sysreg

Add a missing hypervisor event call for hyp_enter on sysreg trapping,
causing an unbalanced hyp_enter/hyp_exit.

The enum hyp_enter_exit_reason is not ABI, so we can keep the ERET
reasons at the end for clarity.

Fixes: 696dfec22b8e ("KVM: arm64: Add hyp_enter/hyp_exit events to nVHE/pKVM hyp")
Signed-off-by: Vincent Donnefort <vdonnefort@google.com>
Reviewed-by: Fuad Tabba <tabba@google.com>
Tested-by: Fuad Tabba <tabba@google.com>
Link: https://patch.msgid.link/20260617095238.1530121-1-vdonnefort@google.com
Signed-off-by: Marc Zyngier <maz@kernel.org>