Update the NOR flash support for TS-7200.

The TS-7200 models all have 16-bit NOR flash.  Update the platform
init to support this.

Remove the private TS72XX_NOR_* defines and use the common ep93xx
defines for the external chip select physical base address instead.

Move the NOR flash registration into a static __init function.  When
the NAND flash support is updated this function will also be used
to register the NAND flash for the TS-7250 and TS-7260.
Tested-by: Matthieu Crapet <mcrapet@gmail.com>
Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>