cfm: Expose detailed fault status in the database.

cfm: Expose detailed fault status in the database.

The cfm_fault column of the database is the logical OR of a number
of reasons that CFM can be in a faulted state.  A controller may
want to have more specific information in which case it can look at
the cfm_fault_status column which this patch adds.

Signed-off-by: Ethan Jackson <ethan@nicira.com>