ARM i.MX imx21ads: Fix overlapping static i/o mappings

The statically defined I/O memory regions for the i.MX21 on chip
peripherals and the on board I/O peripherals of the i.MX21ADS board
overlap. This results in a kernel crash during startup. This is fixed
by reducing the memory range for the on board I/O peripherals to the
actually required range.

Signed-off-by: Jaccon Bastiaansen <jaccon.bastiaansen@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Cc: stable <stable@vger.kernel.org>