dt:/bindings: DRA7 ATL (Audio Tracking Logic) clock bindings

Audio Tracking Logic is designed to be used by HD Radio applications to
synchronize the audio output clocks to the baseband clock. ATL can be also
used to track errors between two reference clocks (BWS, AWS) and generate a modulated
clock output which averages to some desired frequency.
In essence ATL is generating a clock to be used by an audio codec and also
to be used by the SoC as MCLK.

To be able to integrate the ATL provided clocks to the clock tree we need
two types of DT binding:
- DT clock nodes to represent the ATL clocks towards the CCF
- binding for the ATL IP itself which is going to handle the hw
  configuration

The reason for this type of setup is that ATL itself is a separate device
in the SoC, it has it's own address space and clock domain. Other IPs can
use the ATL generated clock as their functional clock (McASPs for example)
and external components like audio codecs can also use the very same clock
as their MCLK.

The ATL IP in DRA7 contains 4 ATL instences.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: Tero Kristo <t-kristo@ti.com>