remove OMAP4 support

[oskar.holmlund_ohdata.se]

Summary

I dont see I will have time/motivation* to maintain the support for OMAP4 branch of the ti branch of 32bit ARM SoC.
The major thing to do is fix up the clock support and probably some of the drivers for updates in the device tree.

• TI.com doesnt seem to list the omap4430/4460 on their productpages so dont know if its even active cpu - guess its not.

The distributors stock of omap4430 SoC seems ok for now but have no idea if its legit, non of the major distributors has the SoC listed.
pandaboard org seems to be down for years.

Test Plan

• GENERIC compiled without any issues.

[manu]

I'm pretty sure that the last time I've tested my pandaboard (maybe 4-5 years ago) there were already problems.

[emaste]

I think this is OK - FreeBSD is starting on the path of retiring 32-bit support. ARMv7 support will remain for FreeBSD 15.0, but if a specific SoC isn't working properly today and doesn't have anyone working on it then retiring it now is reasonable.

Should have a Relnotes: Yes at least (as well as relnotes text / UPDATING entry).

[imp]

If it doesn't work, it's been broken long enough for us to retire.
IIRC, though, Oskar was working on making at least some TI SoCs working.
FreeBSD 11 or maybe early 12 was the last time my Pandaboard booted.