ARM: davinci: implement DEBUG_LL port choice

Apart from the necessity to do this change for multi-platform kernels
the previous logic depended on the zImage decompressor to write the
physical and virtual address to a magic memory location.
If the decompressor is unused or not correctly configured for the
current machid, the addruart macro was an infinite loop. Moreover
debugging the early zImage code was not possible either.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
[nsekhar@ti.com: add braces in _DEBUG_LL_ENTRY() macro to fix checkpatch
error. Fix debug port choice config dependency for traditional DaVincis.
Modify debug port config names and add help text.]
Signed-off-by: Sekhar Nori <nsekhar@ti.com>