video, da8xx: move da8xx-fb.h to drivers/video

the da8xx-fb driver works also on am335x boards. So move
the da8xx-fb.h file from arch/arm/include/asm/arch-davinci
to drivers/video, so this driver can used from am335x
based boards. Also add WVGA panel_type.

Signed-off-by: Heiko Schocher <hs@denx.de>
Cc: Stefano Babic <sbabic@denx.de>
Cc: Anatolij Gustschin <agust@denx.de>
Cc: Tom Rini <trini@ti.com>
Acked-by: Tom Rini <trini@ti.com>