sunhme: Allow usage on SBI based SBus systems

To prevent the SBus driver for Sun Happy Meal cards from being loaded for
PCI cards utilizing the same chipset, a filter was added to the probe
function in commit 0b492fce.

The filter was implemented by checking the name of the parent node in
the OF tree. This patch extends this filter, so that the driver will
load on SBus systems that are based upon SBI SBus Bridges.

Signed-off-by: Kjetil Oftedal <oftedal@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>