[PATCH][next] mt76: fix less than zero check on a u8 variable

[Colin King <colin.king@canonical.com>]

From: Colin Ian King <colin.king@canonical.com>

The signed return from the call to get_omac_idx is being assigned to the
u8 variable mac_idx and then checked for a negative error condition
which is always going to be false. Fix this by assigning the return to
the int variable ret and checking this instead.

Addresses-Coverity: ("Unsigned compared against 0")
Fixes: 04b8e65922f6 ("mt76: add mac80211 driver for MT7615 PCIe-based chipsets")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
---
 drivers/net/wireless/mediatek/mt76/mt7615/main.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/net/wireless/mediatek/mt76/mt7615/main.c b/drivers/net/wireless/mediatek/mt76/mt7615/main.c
index 80e6b211f60b..460d90d5ed6d 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7615/main.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7615/main.c
@@ -77,11 +77,12 @@ static int mt7615_add_interface(struct ieee80211_hw *hw,
 		goto out;
 	}
 
-	mvif->omac_idx = get_omac_idx(vif->type, dev->omac_mask);
-	if (mvif->omac_idx < 0) {
+	ret = get_omac_idx(vif->type, dev->omac_mask);
+	if (ret < 0) {
 		ret = -ENOSPC;
 		goto out;
 	}
+	mvif->omac_idx = ret;
 
 	/* TODO: DBDC support. Use band 0 and wmm 0 for now */
 	mvif->band_idx = 0;
-- 
2.20.1