openib_common: reorganize provider code base to share common mem, cq, qp, dto functions

openib_common: reorganize provider code base to share common mem, cq, qp, dto functions

add new openib_common directory with cq, qp, util, dto, mem function calls
and definitions. This basically leaves the unique CM and Device definitions
and functions to the individual providers directory of openib_scm and openib_cma.

modifications to dapl_cr_accept required. ep->cm_handle is allocated
and managed entirely in provider so dapl common code should not update
ep_handle->cm_handle from the cr->cm_handle automatically. The provider
should determine which cm_handle is required for the accept.

openib_cma defines _OPENIB_CMA_ and openib_scm defines _OPENIB_SCM_ for provider
specific build needs in common code.