MAINTAINERS: Drop myself to reviewer for ravb driver

Maintenance of the ravb driver will be handled by Niklas for now. I
still intend to review patches, and will be using my own email address
going forward.

Signed-off-by: Paul Barker <[e-mail]>
Acked-by: Niklas Söderlund <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

MAINTAINERS

···
 F:	drivers/i2c/busses/i2c-emev2.c
 
 RENESAS ETHERNET AVB DRIVER
-M:	Paul Barker <[e-mail]>
 M:	Niklas Söderlund <[e-mail]>
+R:	Paul Barker <[e-mail]>
 L:	[e-mail]
 L:	[e-mail]
 S:	Maintained