ARM: OMAP2+: Remove legacy smsc911x and smc91x GPMC support

When connecting an ethernet chip to the GPMC, such as smc91x
or smsc911x, a GPIO has to be requested to be used as an IRQ
and also the IO memory for a GPMC chip-select.

When booting with DT the chip-select allocation is handled
in a generic manner in the GPMC driver and the GPIO to IRQ
mapping is made by the DT core so this code is not needed
anymore now that mach-omap2 related boards are DT-only.

Signed-off-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
Signed-off-by: Tony Lindgren <tony@atomide.com>