ARM: dts: Add basic support for isee igepv5

With omap5-board-common.dtsi, we can now easily add support for various omap5
board variants. Let's add minimal support for isee igepv5.

So far I've tested that basic things work, such as serial, USB Ethernet, HDMI
and WLAN.

Note that like omap5-uevm, these boards seem to need to reserve 16MB for a
trap section as in commit 03178c66 ("ARM: dts: omap5-evm: Update
available memory to 2032 MB") and also noted in a u-boot commit at
http://marc.info/?l=u-boot&m=134376852603255 and also at
http://patchwork.ozlabs.org/patch/159881/

.

Not sure why this is not needed for omap5-cm-t54.dts, maybe because of
different u-boot configuration.

Signed-off-by: Tony Lindgren <tony@atomide.com>