Looks like thevarious omap5-uevm models and igepv5 are very similar. So let's
create omap5-board-common.dtsi to allow fixing up things properly for mainline
kernel to support all these.

Even if we eventually end up having only PMIC + MMC + eMMC + SDIO WLAN + SATA +
USB + HDMI configuration in the omap5-board-common.dtsi, this is the easiest
way to add support for other boards rather than diffing various versions of
out of tree dts files.

My guess is that also omap5-sbc-t54.dts can use this, but I don't have that
board so that will need to be dealt with later on.
Signed-off-by: Tony Lindgren <tony@atomide.com>