staging/go7007: Fix compilation by re-adding the missing s2250-loader.h

As pointed by Stefan Lippers-Hollmann <s.L-H@gmx.de>,

Commit:	fd9a40da

 broke s2250
compilation.

This patch re-adds the missing s2250-loader.h

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>