osmo_e1f.c: sa4..sa8 bits should be all-1 by default

From ITU-T G.704 Table 5A Note 4:

> Bits S a4 to S a8 (where these are not used) should be set to 1 on
> links crossing an international border.

Change-Id: Id55599a7152a90f85076de810db2a03ac6f3aac1
1 file changed