mel: replace suffix -emgd with -gl for MinnowBoard

Replace "-emgd" suffix with a generic "-gl" for opengl
related packages for MinnowBoard since we are not
building emgd related stuff due to licensing concerns.

Signed-off-by: Yasir-Khan <yasir_khan@mentor.com>
Merge pull request #329 from Yasir-Khan/emgd-remove

mel: replace suffix -emgd with -gl for MinnowBoard