IKVM on AST2400

[Alexander A. Filippov]

Some time ago the obmc-ikvm service was added to the firmware. It causes some
problems on our VESNIN hardware. As it based on AST2400 it does not have support
for IKVM in the DTS. The system log contains messages that create_usbhid.sh is
unable to find some items in the sysfs and then obmc-ikvm service crashes. It
causes fail in QEMU_CI test.

I belive that this issue also present on other platforms based on AST2400. 

IBM Guys: Do you run tests for Palmetto? 
Is there anybody else who uses AST2400?

Well, my proposal is to make the IKVM support optional by moving it to the
distrofeature.

Besides, I've solved these problems for our hardware by adding required kernel
modules and modifying DTS. 
IKVM works, but bring a lot of warnings after the host was shut down while the
VNC-client is still connected.

During the solving I copied some records from aspeed-g5.dtsi to aspeed-g4.dtsi. 
Should I commit these changes to Torvalds or OpenBMC repo?

--
Regards
Alexander Filippov
Software Engineer, YADRO