net: mscc: ocelot: publish ocelot_sys.h to include/soc/mscc

The Felix DSA driver needs to write to SYS_RAM_INIT_RAM_INIT for its own
chip initialization process.

Also update the MAINTAINERS file such that the headers exported by the
ocelot driver are under the same maintainers' umbrella as the driver
itself.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>