dt-bindings: i2c: riic: Rename bindings documentation file

Rename the bindings documentation file for Renesas EMEV2 IIC controller
from i2c-emev2.txt to renesas,iic-emev2.txt.

This is part of an ongoing effort to name bindings documentation files for
Renesas IP blocks consistently, in line with the compat strings they
document.
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

MAINTAINERS

@@ -13628,7 +13628,7 @@ F:	drivers/clk/renesas/
 RENESAS EMEV2 I2C DRIVER
 M:	Wolfram Sang <wsa+renesas@sang-engineering.com>
 S:	Supported
-F:	Documentation/devicetree/bindings/i2c/i2c-emev2.txt
+F:	Documentation/devicetree/bindings/i2c/renesas,iic-emev2.txt
 F:	drivers/i2c/busses/i2c-emev2.c
 
 RENESAS ETHERNET DRIVERS