ARM: dts: OMAP3: reduce GPMC mapped registers address space

ARM: dts: OMAP3: reduce GPMC mapped registers address space

Currently the OMAP General-Purpose Memory Controller (GPMC) device
node maps 16 MB of address space for its hardware registers.

This is because the OMAP Technical Reference Manual says that the
GPMC module register address space size is 16 MB. But in practice
the maximum address offset used by a GPMC register is 0x02d0.

So, there is no need to map such a big address space for GPMC regs.

This change was suggested by Jon Hunter [1].

[1]: https://patchwork.kernel.org/patch/2057111/

Signed-off-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
Acked-by: Jon Hunter <jon-hunter@ti.com>
Signed-off-by: Benoit Cousson <benoit.cousson@linaro.org>