ARM: pxa: prevent PXA270 occasional reboot freezes

Erratum 71 of PXA270M Processor Family Specification Update
(April 19, 2010) explains that watchdog reset time is just
8us insead of 10ms in EMTS.

If SDRAM is not reset, it causes memory bus congestion and
the device hangs.

We put SDRAM in selfresh mode before watchdog reset, removing
potential freezes.

Signed-off-by: Sergei Ianovich <ynvich@gmail.com>
arm: pxa: fix LP-8x4x USB support

Signed-off-by: Sergei Ianovich <ynvich@gmail.com>
arm: pxa: fix 2nd flash chip address on LP-8x4x

Initial configuration has worng address of the second chip.
There is an alias for the 1st chip at 0x02000000 in earlier
verions of LP-8x4x, so the boot normally.

However, new LP-8x4xs have a bigger 1st flash chip, and hang on
boot without this patch.

Signed-off-by: Sergei Ianovich <ynvich@gmail.com>
arm: pxa: update LP-8x4x to boot DT kernel

Signed-off-by: Sergei Ianovich <ynvich@gmail.com>
arm: pxa: init ethaddr for LP-8x4x using DT

When DT define aliases for etherner0 and ethernet1, U-Boot
automatically patched MAC addresses using ethaddr and eth1addr
environment variables respectively.

Custom initialization is no longer needed.

Signed-off-by: Sergei Ianovich <ynvich@gmail.com>
CC: Marek Vasut <marex@denx.de>