smc91x: fix compile error when SMC_DEBUG >= 2

When SMC_DEBUG >= 2, we hit the following compilation error:

drivers/net/ethernet/smsc/smc91x.c:85:0:
drivers/net/ethernet/smsc/smc91x.c: In function ‘smc_findirq’:
drivers/net/ethernet/smsc/smc91x.c:1784:9: error: ‘dev’ undeclared (first use in this function)
  DBG(2, dev, "%s: %s\n", CARDNAME, __func__);
         ^
Fix it by passing in the appropriate netdev pointer.

Signed-off-by: Zi Shen Lim <zlim.lnx@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>