smc91111: use SSYNC() rather than asm(ssync) for Blackfin

Since the "ssync" instruction may have hardware anomalies associated with
it, have the smc91111 driver use the SSYNC macro rather than invoking it
directly.  We workaround all the anomalies via this macro.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>