isdn/hisax: remove set but not used variable 'total'

Fixes gcc '-Wunused-but-set-variable' warning:

drivers/isdn/hisax/hfc_pci.c:277:6: warning:
 variable ‘total’ set but not used [-Wunused-but-set-variable]

It never used since git history start.

Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>