ASoc: msm : update speaker gain control.

Configuring speaker max gain as 8 in the SPKR_DRV_GAIN register.
Other wise the gain setting when the invert flag is set will differ.

Change-Id: I18ae30c4035088fd439ae00bba2a34aa4e9385a9
CRs-Fixed: 593181
Signed-off-by: Mohammad Johny Shaik <mjshai@codeaurora.org>