vswitch.ovsschema: Correct schema version number.

Commit 3e5aeeb581faf7 (bridge: Keep bond active slave selection across OVS
restart) updated the OVS schema number from 7.9.0 to 8.0.0.  However,
the major version number should only be incremented for incompatible schema
changes, ones that are likely to break software that interacts with the
schema.  The change in question only added a column to a table, so it is
not an incompatible change.  Therefore, this commit changes the schema
version number to 7.10.0, indicating a compatible change.

Signed-off-by: Ben Pfaff <blp@nicira.com>
Acked-by: Andy Zhou <azhou@nicira.com>