KVM: selftests: Add test for KVM_REG_ARM_VENDOR_HYP_BMAP_2

KVM: selftests: Add test for KVM_REG_ARM_VENDOR_HYP_BMAP_2

One difference here with other pseudo-firmware bitmap registers
is that the default/reset value for the supported hypercall
function-ids is 0 at present. Hence, modify the test accordingly.

Reviewed-by: Sebastian Ott <sebott@redhat.com>
Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
Link: https://lore.kernel.org/r/20250221140229.12588-7-shameerali.kolothum.thodi@huawei.com
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>