hw/intc/arm_gicv3_kvm: Check KVM_DEV_ARM_VGIC_GRP_CPU_SYSREGS in reset

hw/intc/arm_gicv3_kvm: Check KVM_DEV_ARM_VGIC_GRP_CPU_SYSREGS in reset

KVM_DEV_ARM_VGIC_GRP_CPU_SYSREGS needs to be checked before
attempting to read ICC_CTLR_EL1; otherwise kernel versions not
exposing this kvm device group will be incompatible with qemu 2.9.

Fixes: 07a5628  ("hw/intc/arm_gicv3_kvm: Reset GICv3 cpu interface registers")
Signed-off-by: Eric Auger <[email protected]>
Reported-by: Prakash B <[email protected]>
Tested-by: Alexander Graf <[email protected]>
Message-id: 1490721640[email protected]
Signed-off-by: Peter Maydell <[email protected]>