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

drivers/net/ethernet/qlogic/qlcnic/qlcnic.h

@@ -430,7 +430,7 @@ struct qlcnic_hardware_context {
 	u8 diag_test;
 	u8 num_msix;
 	u8 nic_mode;
-	char diag_cnt;
+	int diag_cnt;
 
 	u16 max_uc_count;
 	u16 port_type;