ARM: mxs: Consolidate configuration options

Pull all the duplicate configuration options into configs/mxs.h
from the board configuration files. This reduces the files greatly
and makes them somewhat more readable. Besides, we do no longer
have such a horrible duplication of code.

Note that the mx23evk grew in size slightly. This is due to the
CONFIG_SYS_CBSIZE now being set to 1024 as it is on the rest of
MXS systems.

This patch also fixes the OCRAM size for i.MX23. The i.MX23 has
only 32kB of OCRAM, while i.MX28 has 128kB of OCRAM.

I verified the configuration didn't change for each of the boards,
but I didn't boot-test it on the boards I do not have. I configured
U-Boot for each board using the "make ... <board>_config" command
and then ran "cpp -I include -dM include/config.h" , which dumped
all the configuration options. I did this both before and after this
patch and finally compared the results for each MXS board. Actually,
the results do differ slightly, since the configs/mxs.h file now
properly includes the correct iomux-mx23.h or iomux-mx28.h , so
while comparing, I had to ignore these new defines. These have no
impact on U-Boot configuration though.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Fabio Estevam <fabio.estevam@freescale.com>
Cc: Lauri Hintsala <lauri.hintsala@bluegiga.com>
Cc: Otavio Salvador <otavio@ossystems.com.br>
Cc: Stefano Babic <sbabic@denx.de>