ANDROID: GKI: SoC: core: Introduce macro SOC_SINGLE_MULTI_EXT

For some of the mixer controls, client would like to register
count as a parameter. Macro adds support to specify the count.

Test: build
Bug: 151372815
Signed-off-by: Banajit Goswami <bgoswami@codeaurora.org>
Signed-off-by: Sudheer Papothi <spapothi@codeaurora.org>
Signed-off-by: Meng Wang <mwang@codeaurora.org>
(cherry picked from commit f6fff00067b98998228d61a8b36873a14bd75bd4)
Signed-off-by: Hridya Valsaraju <hridya@google.com>
Change-Id: I57b891ef99a03cb7b5b860e96cf2fc9916073166