drm/mali: Use new atomic iterator macros

drm/mali: Use new atomic iterator macros

for_each_obj_in_state is about to be removed, so use the new iterator
macros.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Liviu Dudau <liviu.dudau@arm.com>
Cc: Brian Starkey <brian.starkey@arm.com>
Cc: Mali DP Maintainers <malidp@foss.arm.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170712081344.25495-12-maarten.lankhorst@linux.intel.com
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Acked-by: Liviu Dudau <liviu.dudau@arm.com>