video: da8xx-fb: remove unneeded "var" initialization

modedb helper now updates "var" information based on the detected
panel, remove the unnecessary initialization.

Signed-off-by: Afzal Mohammed <afzal@ti.com>
Signed-off-by: Darren Etheridge <detheridge@ti.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>