MAINTAINERS: update list of qtnfmac maintainers

Removing Avinash since tomorrow is his last day at Quantenna.
Signed-off-by: Sergey Matyukevich <sergey.matyukevich.os@quantenna.com>
Signed-off-by: Igor Mitsyanko <igor.mitsyanko.os@quantenna.com>
Signed-off-by: Avinash Patil <avinashp@quantenna.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20200416182803.31201-1-sergey.matyukevich.os@quantenna.com

MAINTAINERS

@@ -14050,7 +14050,6 @@ F:	drivers/net/wireless/ath/wcn36xx/
 
 QUANTENNA QTNFMAC WIRELESS DRIVER
 M:	Igor Mitsyanko <imitsyanko@quantenna.com>
-M:	Avinash Patil <avinashp@quantenna.com>
 M:	Sergey Matyukevich <smatyukevich@quantenna.com>
 L:	linux-wireless@vger.kernel.org
 S:	Maintained