The patch extends the Amstrad Delta LCD panel driver with optional support for
changing contrast using standard LCD class device API instead of setting it
silently to a default value at panel enable. It also allows for lowering power
consumption by turning off OMAP_PWL_CLK_ENABLE via lcd_ops.set_power callback.

Created and tested against linux-omap for-next,
commit 155a75d9725e66e5ec8a383822957dee52427057.
Signed-off-by: NJanusz Krzysztofik <jkrzyszt@tis.icnet.pl>
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@nokia.com>