msm: synx: Fix external type and pointer check

Fix the check made if the external object is of valid
type and can be bound to synx object.
Also, fix the check to verify if the provided pointer
to pass the newly created synx object id is valid.

Change-Id: I1a2a5c777ff0948ebe5ab638d884db2b08de2d43
Signed-off-by: Sumukh Hallymysore Ravindra <shallymy@codeaurora.org>