audio-lnx: Enable apr-dummy compilation for sdm450

apr_dummy module is added to trigger probe of
deferred modules during sound card registration.
Enable the same for CONFIG_MSM_QDSP6_APRV2 config.

CRs-Fixed: 2165343
Change-Id: I3fa10703b7b1150198b4498a82d1bde35cb7ae5b
Signed-off-by: Soumya Managoli <smanag@codeaurora.org>