omap3: add useful dss defines

Add useful omap3 dss defines for: polarity, TFT data lines, lcd
display type, gfx burst size, and gfx format

Cc: Anatolij Gustschin <agust@denx.de>
Cc: Jeroen Hofstee <jeroen@myspectrum.nl>
Cc: Tom Rini <trini@ti.com>
Cc: Wolfgang Denk <wd@denx.de>
Signed-off-by: Nikita Kiryanov <nikita@compulab.co.il>
Signed-off-by: Igor Grinberg <grinberg@compulab.co.il>