MAINTAINERS: i2c mv64xxx: Update documentation path

Update MAINTAINERS record to reflect the file move
from i2c-mv64xxx.txt to marvell,mv64xxx-i2c.yaml.

Fixes: f8bbde72

 ("dt-bindings: i2c: mv64xxx: Add YAML schemas")
Signed-off-by: Denis Efremov <efremov@linux.com>
Acked-by: Maxime Ripard <mripard@kernel.org>
Acked-by: Gregory CLEMENT <gregory.clement@bootlin.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>