mt7601u: fix bbp version check in mt7601u_wait_bbp_ready

Fix bbp ready check in mt7601u_wait_bbp_ready. The issue is reported by
coverity with the following error:

Logical vs. bitwise operator
The expression's value does not depend on the operands; inadvertent use
of the wrong operator is a likely logic error.

Addresses-Coverity-ID: 1309441 ("Logical vs. bitwise operator")
Fixes: c869f77d ("add mt7601u driver")
Acked-by: Jakub Kicinski <kubakici@wp.pl>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/mediatek/mt7601u/phy.c

@@ -213,7 +213,7 @@ int mt7601u_wait_bbp_ready(struct mt7601u_dev *dev)
 
 	do {
 		val = mt7601u_bbp_rr(dev, MT_BBP_REG_VERSION);
-		if (val && ~val)
+		if (val && val != 0xff)
 			break;
 	} while (--i);