i2c: octeon: thunderx: Add MAINTAINERS entry

The i2c Octeon and ThunderX drivers are maintained by Cavium.
While at it fix the whitespace errors of the next entry.

Signed-off-by: Jan Glauber <jglauber@cavium.com>
Acked-by: David Daney <david.daney@cavium.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>