ipod Classic: implement HAVE_RECORDING

This patch has been tested on iPod 80 and 160slim, actually
it works but some updates must be done to the final version:

 - unlimitted input buffer
 - decrease CHUNK_SIZE
 - use non-cached addresses instead of discard d-cache ???

Capture hardware versions:

 Ver  iPod models   capture support
 ---  -----------   ---------------
 0    80/160fat     dock line-in
 1    120/160slim   dock line-in + jack mic

 HW version 1 includes an amplifier for the jack plug mic.

 Capture HW detection only tested on iPod 80 and 160slim.

CODEC power:

 AFAIK, OF powers CS42L55 at VA=2.4V for capture (1.8V for
 playback) and turns on the ADC charge pump. CODEC datasheet
 recommmends to disable the charge pump for VA>2.1V.

 CS42L55 DS, s4.13 (Required Initialization Settings): for
 VA>2.1V, some adjustments "must" be done using undocummented
 "control port compensation" registers. OF does not modifies
 these registers when VA=2.4V.

 This patch configures capture HW in the same way as OF does.

TODO:
 - ADC full scale voltage depends on VA, perform tests to find
   clipping levels for VA=1.8V and VA=2.4V

Change-Id: I7e20fd3ecaa83b1c58d5c746f5153fe5c3891d75

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