meta-ibm restructuring

[Brad Bishop]

the meta-witherspoon layer in meta-ibm supports a number of machine targets beyond witherspoon.  the meta-ibm layer itself is nearly empty.  This is confusing to say the least, so I am doing some restructuring in the meta-ibm layer such that everything will simply be in meta-ibm:

https://gerrit.openbmc-project.xyz/c/openbmc/meta-ibm/+/27263

Please let me know if you have any concerns.

thx - brad