sb1000: fix variable set but not used warnings

GCC 8 complains:

drivers/net/sb1000.c: In function ‘card_send_command’:
drivers/net/sb1000.c:319:14: warning: variable ‘x’ set but not used [-Wunused-but-set-variable]
  int status, x;
              ^
drivers/net/sb1000.c: In function ‘sb1000_check_CRC’:
drivers/net/sb1000.c:493:6: warning: variable ‘crc’ set but not used [-Wunused-but-set-variable]
  int crc, status;
      ^~~

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Dirk van der Merwe <dirk.vandermerwe@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>