arm: detect SoC timer from FDT for OMAP3 and PXA

Change-Id: Ib03a11f016cb937d748d2696a17158e17c86e317
Reviewed-on: https://review.haiku-os.org/c/haiku/+/5522
Tested-by: Commit checker robot <no-reply+buildbot@haiku-os.org>
Reviewed-by: David Karoly <karolyd577@gmail.com>