[PATCH] drm: Fix issue reported by Coverity in drivers/char/drm/via_irq.c

This patch tries to fix an issue reported in drivers/char/drm/via_irq.c by
Coverity, please review and apply if correct.

Error reported:
CID: 3444 Checker: REVERSE_INULL (help)
File: /export2/p4-coverity/mc2/linux26/drivers/char/drm/via_irq.c
Function: via_driver_irq_wait
Description: Pointer "dev_priv" dereferenced before NULL check

Patch Description:
 Move de-referencing dev_priv to after the NULL check.

Signed-off-by: Jayachandran C. <c.jayachandran at gmail.com>
Signed-off-by: Dave Airlie <airlied@linux.ie>