[gta02-core] More audio considerations

[Christoph Mair]

> If we can confirm that the LDOs handle overcurrent gracefully, then I
> think the reordering of LDOs looks like the most promising choice.
> E.g., swap LDO2 (CODEC_3V3, 50 mA, off in Standby) and LDO4 (BT_3V2,
> 150 mA, 2.8V in Standby).
Last monday I accidentally tried what happens when trying to boot with IO_3V3 
shorted to GND (caused by a bad solder joint at the aux switch).

I could observe two possible behaviours before finding my mistake:
a) Qi booted, loaded the kernel and after some time I got a kernel panic (AUX-
LED flashing). Then I removed the battery. The screen backlight did not turn 
on.

b) Qi boots, then nothing happens. Probably the PMU turned everything off.

I did not connect the serial console to see what happens, but my scope showed 
some activity on the serial lines.

> If they can't handle overcurrent, then we'd probably need an external
> LDO with switch.
I think they probably can until the device becomes too hot and turns off 
everything.

Christoph