video: sa1100fb: use devm_request_irq()

Use devm_request_irq() to request the interrupt (a little earlier too)
so we can avoid having to manually clean this up.

Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>