ARM: OMAP2+: Show bootloader GPMC timings to allow configuring the .dts file

As we still have some devices with GPMC timings missing from the
.dts files, let's make it a bit easier to use the bootloader
values and print them out.

Note that we now need to move the parsing of the device tree provided
configuration a bit earlier so we can use that for checking if anything
was configured.

Acked-by: Roger Quadros <rogerq@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>