net: qlcnic: remove unused variable 'val' in qlcnic_83xx_cam_unlock()

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

drivers/net/ethernet/qlogic/qlcnic/qlcnic_83xx_hw.c:661:6: warning:
 variable 'val' set but not used [-Wunused-but-set-variable]
  661 |  u32 val;
      |      ^~~

After commit 7f966452 ("qlcnic: 83xx memory map and HW access
routines"), variable 'val' is never used in qlcnic_83xx_cam_unlock(), so
removing it to avoid build warning.

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Zhang Changzhong <zhangchangzhong@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>