memory: omap-gpmc: Fix parsing of devices

We currently artificially limit the parsing of GPMC connected
devices based on the device name. Let's stop doing that, it's
confusing as adding devices to .dts files with using normal
names like fpga and usb will currently cause them to not probe.

Cc: Roger Quadros <rogerq@ti.com>
Reported-by: Brian Hutchinson <b.hutchman@gmail.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>