qlcnic: Fix warning reported by kbuild test robot.

drivers/net/ethernet/qlogic/qlcnic/qlcnic_io.c: In function 'qlcnic_handle_fw_message':
drivers/net/ethernet/qlogic/qlcnic/qlcnic_io.c:922:4: warning: overflow in implicit constant conversion [-Woverflow]

Signed-off-by: Jitendra Kalsaria <jitendra.kalsaria@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>