net: cxgb4: fix return error value in t4_prep_fw

t4_prep_fw goto bye tag with positive return value when something
bad happened and which can not free resource in adap_init0.
so fix it to return negative value.

Fixes: 16e47624 ("cxgb4: Add new scheme to update T4/T5 firmware")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Li Heng <liheng40@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/chelsio/cxgb4/t4_hw.c

@@ -3493,7 +3493,7 @@ int t4_prep_fw(struct adapter *adap, struct fw_info *fw_info,
 	drv_fw = &fw_info->fw_hdr;
 
 	/* Read the header of the firmware on the card */
-	ret = -t4_read_flash(adap, FLASH_FW_START,
+	ret = t4_read_flash(adap, FLASH_FW_START,
 			    sizeof(*card_fw) / sizeof(uint32_t),
 			    (uint32_t *)card_fw, 1);
 	if (ret == 0) {
@@ -3522,7 +3522,7 @@ int t4_prep_fw(struct adapter *adap, struct fw_info *fw_info,
 		   should_install_fs_fw(adap, card_fw_usable,
 					be32_to_cpu(fs_fw->fw_ver),
 					be32_to_cpu(card_fw->fw_ver))) {
-		ret = -t4_fw_upgrade(adap, adap->mbox, fw_data,
+		ret = t4_fw_upgrade(adap, adap->mbox, fw_data,
 				    fw_size, 0);
 		if (ret != 0) {
 			dev_err(adap->pdev_dev,
@@ -3554,7 +3554,7 @@ int t4_prep_fw(struct adapter *adap, struct fw_info *fw_info,
 			FW_HDR_FW_VER_MICRO_G(c), FW_HDR_FW_VER_BUILD_G(c),
 			FW_HDR_FW_VER_MAJOR_G(k), FW_HDR_FW_VER_MINOR_G(k),
 			FW_HDR_FW_VER_MICRO_G(k), FW_HDR_FW_VER_BUILD_G(k));
-		ret = EINVAL;
+		ret = -EINVAL;
 		goto bye;
 	}