staging: gma500: Fix warning in power.c

 gma_resume_display() wants 'struct pci_dev *' as it's parameter, so lets pass dev->pdev instead of dev. Fixes the following warning.

drivers/staging/gma500/power.c: In function ‘gma_power_begin’:
drivers/staging/gma500/power.c:269:3: warning: passing argument 1 of ‘gma_resume_display’ from incompatible pointer type
drivers/staging/gma500/power.c:99:13: note: expected ‘struct pci_dev *’ but argument is of type ‘struct drm_device *’

Signed-off-by: Rakib Mullick <rakib.mullick@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>