MAINTAINERS: use proper email for my I2C work

Renesas is solely funding my I2C maintenance meanwhile, give them credit
for that by using this email address.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>

MAINTAINERS

@@ -9988,7 +9988,7 @@ F:	Documentation/i2c/busses/i2c-parport.rst
 F:	drivers/i2c/busses/i2c-parport.c
 
 I2C SUBSYSTEM
-M:	Wolfram Sang <wsa@kernel.org>
+M:	Wolfram Sang <wsa+renesas@sang-engineering.com>
 L:	linux-i2c@vger.kernel.org
 S:	Maintained
 W:	https://i2c.wiki.kernel.org/