audio-lnx: Fix re-compile issue for dlkm

On incremental build, Module.symver used
will be older. Add commands to delete symver
files before recompile starts for audio kernel.

Change-Id: I1e90ad4543a7a06b5940f0a2612d18ed722ecd55
Signed-off-by: Laxminath Kasam <lkasam@codeaurora.org>