char: msm_smd_pkt: Remove legacy device init functionality

The legacy device initialization functionality, which was used in cases
where the DT was not used for initialization, is no longer used.

Remove this functionality.

Change-Id: Ib10344050656a1e8b624c4fdc709082d2985379f
Signed-off-by: Steven Cahail <scahail@codeaurora.org>