[ARM] 4887/1: i.MXC family: Separate current platform code

[ARM] 4887/1: i.MXC family: Separate current platform code

From: Juergen Beisert <j.beisert@pengutronix.de>

This patch separates the current code into i.MX2 and i.MX3 and modifies
the Kconfig files to reflect this separation in the menus.

Things happend since last review:
 - make i.MX3 compile again
 - fix some structure names to be conform with all the shared/common
   sources from i.MX1/i.MX2

Previous changes:
 - stay conform to other Kconfig files (note from Russell King)

Signed-off-by: Juergen Beisert <j.beisert@pengutronix.de>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>