MAINTAINERS: switch to my private email for Renesas Ethernet drivers

I no longer work for Cogent Embedded (but my old email still works :-)),
and still would like to continue looking after the Renesas Ethernet drivers
and bindings. Let's switch to my private email.

Signed-off-by: Sergei Shtylyov <[e-mail]>
Acked-by: Geert Uytterhoeven <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

MAINTAINERS

···
 F:	drivers/i2c/busses/i2c-emev2.c
 
 RENESAS ETHERNET DRIVERS
-R:	Sergei Shtylyov <[e-mail]>
+R:	Sergei Shtylyov <[e-mail]>
 L:	[e-mail]
 L:	[e-mail]
 F:	Documentation/devicetree/bindings/net/renesas,*.txt