shared.cfg.guest-hw: Update pf_assignable and vf_assignable configure to fit framework changes.

pf_assignable and vf_assignable variants only works with nettype = bridge

Signed-off-by: Feng Yang <fyang@redhat.com>
qemu.tests: Add sr_iov_sanity new test case.

Signed-off-by: Feng Yang <fyang@redhat.com>