net: smsc911x: Remove unused variables

Fixes the following W=1 kernel build warning(s):

 drivers/net/ethernet/smsc/smsc911x.c: In function ‘smsc911x_rx_fastforward’:
 drivers/net/ethernet/smsc/smsc911x.c:1199:16: warning: variable ‘temp’ set but not used [-Wunused-but-set-variable]

 drivers/net/ethernet/smsc/smsc911x.c: In function ‘smsc911x_eeprom_write_location’:
 drivers/net/ethernet/smsc/smsc911x.c:2058:6: warning: variable ‘temp’ set but not used [-Wunused-but-set-variable]

Signed-off-by: Wei Xu <xuwei5@hisilicon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>