ipc: remove UAPI header copy

The UAPI headers will be copied from the include/uapi directory.
Remove support to copy the header files from ipc location.

Change-Id: Ie7e92942e476fdfd16c0b0d226c40e90ae9da0c4
Signed-off-by: Banajit Goswami <bgoswami@codeaurora.org>