patches for review, Xenomai core porting for kernel 5.4.y

[Meng, Fino]

Hi all & Jan,

I just sent out the 4 patches again by git send-email, I applied them on branch : next 

And the IPIPE part is hosting here for review: 
https://github.com/intel/linux-stable-xenomai/tree/review/5.4.59/stable/ipipe-x86

combine these 2 parts,  build and boot is OK, latency run OK. 
switchtest show error,  some other smokey test may also fail, and I hope can fix them ASAP.


BR / Fino (孟祥夫)
Intel – IOTG Developer Enabling