Removes some functions that are not used anywhere:
armada_drm_encoder_mode_fixup() armada_drm_encoder_commit() armada_drm_encoder_prepare()

This was partially found by using a static code analysis program called cppcheck.
Signed-off-by: NRickard Strandqvist <rickard_strandqvist@spectrumdigital.se>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>