ENGR00141152-1 header file: make default display option

ENGR00141152-1 header file: make default display option

After this patch, default display for below platforms:

mx51 bbg: DVI-XGA on DI0
mx53 ard:  LVDS-XGA on DI0
mx53 evk: CLAA-WVGA on DI0
mx53 loco: VGA-XGA on DI1
mx53 smd: LVDS-XGA on DI1

The default options will work if you do not enter other video cmdline options.
For platform need enable other drivers, it will enable it automatically.
For example, under default option, mx53 loco will enable tve-vga driver
automatically; before this patch, it need add 'vga' to cmdline to enable it.
And 'di1_primary' option also will be enabled automatically if need.

If you want to overwrite the default option, please refer to below:

enable vga: 'vga'
disable vga: 'vga=off'
enable tve: 'tve'
disable tve:  'tve=off'
enable ddc: 'ddc'
disable ddc: 'ddc=off'
enable hdmi: 'hdmi'
disable hdmi: 'hdmi=off'
choose di0 as primary: 'di0_primary'
choose di1 as primary: 'di1_primary'

Signed-off-by: Jason Chen <b02280@freescale.com>