ASoC: msm8960: Use all external speaker pins.

Speaker Function control is a master control used for muting
external speakers. After splitting speaker widget to 4 widgets
representing + and - inputs of stereo speaker, speaker function
control should enable and disable all 4 widgets at the same
time.

CRs-fixed: 312165
Change-Id: Ia30b1969467b0f2a6fdf0f9049c75ef363f2be8c
Signed-off-by: Peter Lohmann <plohmann@codeaurora.org>