msm: ipa: Prevent multiple header deletion from user space

An IPA header or processing context can be added once
and later deleted once from user space.
Multiple deletion may cause invalid state of the headers
software cache.

Change-Id: Ic0b8472b7fd8a76233a007d90c832af726184574
CRs-fixed: 1097714
Signed-off-by: Ghanim Fodi <gfodi@codeaurora.org>