[media] davinci: vpif: make request_irq flags as shared

omap-l138 shares the interrupt between capture and display.
Make sure we are able to request for the same irq number
by making a shared irq request.

Signed-off-by: Manjunath Hadli <manjunath.hadli@ti.com>
Signed-off-by: Lad, Prabhakar <prabhakar.lad@ti.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>