ARM: OMAP2+: Fix GPMC and simplify bootloader timings for 8250 and smc91x

Commit f2bf0e72 (ARM: OMAP2+: Add minimal 8250 support
for GPMC) added support for using bootloader timings for some
devices. Turns out we can do the same by looking at the compatible
flags of the child without adding a new function as smc91x has
a similar issue as 8250 with the bootloader timings.

And let's fix the 8250 naming, we should use the device type as
the name like uart instead of 8250 for zoom dts file.

Cc: "Benoît Cousson" <bcousson@baylibre.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>