Use mce-plugin-libhybris for frame buffer power control

If mce-plugin-libhybris is installed and support for frame buffer
power control is available, the mce display plugin will utilize it.

[mce] Support frame buffer power control via mce-plugin-libhybris
Merge pull request #55 from spiiroin/fb_power_via_libhybris

Use mce-plugin-libhybris for frame buffer power control