hal: Add static internal function at the top of the file

-Add check_and_set_gapless_mode and get_offload_buffer_size functions
 at the begining of hal file.

Change-Id: I134dffac4aa81ed52fc6a2668cb53fbda60103ca
post_proc: Enable effects param in DSP to start effect

-During switch to tunnel playback, offload effects-flags remain
disabled. This stops effects being applied on tunnel playback.
-Send effects enable params to DSP to start effects during switch.

Change-Id: Ibe1e50b41ca25b51537e4a0ad80dbd5184379133
CRs-Fixed: 593509
policy_hal: Correct device selection in STRATEGY_ENFORCED_AUDIBLE

- When strategy is STRATEGY_ENFORCED_AUDIBLE, do not select
  unsupported combo devices Proxy+Speaker, HDMI+Speaker,
  and FM_TX + Speaker.

Change-Id: Icd4f6de74807a6efc5f6eb8258c020ad990aaf9b
Crs-fixed: 600799
post_proc: disable adsp reverb when preset is 'None'

Audio HAL set corresponding preset id into adsp, but doesn't disabe
reverb explicitly when 'None' preset is chosen. However, preset=0
means custom preset in adsp, so adsp won't stop reverb processing.

Change-Id: I0c42dd13c09579a6bd3bef2141b857477ec65f2e
CRs-Fixed: 604982
audio-caf: legacy: Sync FM flag with ALSA

 * Use QCOM_FM_ENABLED instead of BOARD_HAVE_QCOM_FM.
 * Also, guess what's the only platform using the msm7x30 audio HAL.

Change-Id: If5226d029ffa6ac88e27cb7ed2b1cf000c597f3f