contrib: setup build env: use rev. 11 for n3xx
contrib: setup build env: use rev. 11 for n3xx

set MACHINE=ni-sulfur-rev11-mender when using device_type=n3xx

Signed-off-by: Joerg Hofrichter <64f05fd09614173ff715799ea05b4b0d8fbec0da@ni.com>

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