KVM: arm/arm64: vgic: Cap SPIs to the VM-defined maximum

commit bea2ef803ade3359026d5d357348842bca9edcf1 upstream.

SPIs should be checked against the VMs specific configuration, and
not the architectural maximum.

Cc: stable@vger.kernel.org
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>