net: qualcomm: rmnet: remove set but not used variables 'ip_family, fc_seq, qos_id'

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

drivers/net/ethernet/qualcomm/rmnet/rmnet_map_command.c:26:6:
 warning: variable 'ip_family' set but not used [-Wunused-but-set-variable]
drivers/net/ethernet/qualcomm/rmnet/rmnet_map_command.c:27:6:
 warning: variable 'fc_seq' set but not used [-Wunused-but-set-variable]
drivers/net/ethernet/qualcomm/rmnet/rmnet_map_command.c:28:6:
 warning: variable 'qos_id' set but not used [-Wunused-but-set-variable]

It never used since introduction in commit
ceed73a2 ("drivers: net: ethernet: qualcomm: rmnet: Initial implementation")

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