Status quo is that initially a size of 64 MiB is assumed (which is also
used to determine the size of the malloc area) and then later the dtb
is fixed up with the actually available RAM which is then used.

Instead detect the real RAM size earlier and don't fixup the device tree.
The device tree is fixed up instead by generic code. This way the malloc
area is more appropriately sized and RAM detection is more similar to mach-imx
which is both nice.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

Currently only second stage booting from the vendor U-Boot is tested. I
don't want to flash barebox into NAND yet because UART-booting for
recovery doesn't work for me.

Working so far are:

 - UART
 - networking
 - nand flash

Signed-off-by: Uwe Kleine-König <uwe@kleine-koenig.org>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>