tools: Add missing formats keyword to segment-routing in frr-reload

tools: Add missing formats keyword to segment-routing in frr-reload

When reloading the following configuration:
```
segment-routing
 srv6
  formats
   format usid-f3216
     wide-local-id-block explicit start 100
   exit
   !
   format uncompressed-f4024
   exit
   !
  exit
  !
 exit
 !
exit
```
frr-reload.py does not properly enter the `formats` context. Because of this,
it fails with an unknown command error when applying new or updating format
configuration.

Signed-off-by: Jonathan Voss <jvoss@onvox.net>