meta-ettus-core: recipes-support: uhd: Update cmake flags for MPM
meta-ettus-core: recipes-support: uhd: Update cmake flags for MPM

MPM_PYTHON_VER is deprecated, now that we only support Python 3.
Remove said flag.

[Moritz: Adapted from meta-ettus rocko/n3xx branch]
Signed-off-by: Martin Braun <3d56405a74868c0c3ff5cba6e886d82741a922ab@ettus.com>
Signed-off-by: Moritz Fischer <16c4312f096cb05ec900643fe7a5f22f7761ab4a@ettus.com>

EttusResearch/meta-ettus,EttusResearch/meta-ettus,EttusResearch/meta-ettus,EttusResearch/meta-ettus,EttusResearch/meta-ettus,EttusResearch/meta-ettus