hal: Avoid configurable mono for target with single speaker

Do not allow configurable mono speaker assignment for devices with
one speaker. For msm8998, avoid it for fluid variants.Also, fix typo
in selection of VOICE_SPEAKER_2_PROTECTED device during send_voice_cal.

CRs-Fixed: 1082853
Change-Id: I7124c7ca7424feea1f2e54bcb6bc581313df6259