MAINTAINERS: update qtnfmac maintainers

I am leaving Quantenna, so I will no longer have access to firmware and
hardware. Meanwhile I plan to participate in reviewing qtnfmac patches
for a while until my firmware knowledge becomes completely obsolete.
Adding myself as a reviewer using my personal email address.

Signed-off-by: Sergey Matyukevich <[email protected]>
Signed-off-by: Igor Mitsyanko <[email protected]>
Signed-off-by: Kalle Valo <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

MAINTAINERS

@@ -14066,7 +14066,7 @@ F:	drivers/net/wireless/ath/wcn36xx/
 
 QUANTENNA QTNFMAC WIRELESS DRIVER
 M:	Igor Mitsyanko <[email protected]>
-M:	Sergey Matyukevich <smatyukevich@quantenna.com>
+R:	Sergey Matyukevich <geomatsi@gmail.com>
 L:	[email protected]
 S:	Maintained
 F:	drivers/net/wireless/quantenna