sf: Override presentation layer with ext_only layer

Do not add presentation layer to the external list when external only
layer is present.

Change-Id: I46c8a85a572f88a2d4026c4026d99fd037b928be
(cherry picked from commit 9b39ac80890e77177427acec3f6e423085265491)
(cherry picked from commit d5be54b045571e0b9d139bd1022d922137c13bb9)
(cherry picked from commit a72ea507c0587031910e484d989ab32179a7ddfe)