drm/vc4: replace drm_gem_dma_object for drm_gem_object in vc4_exec_info

The array of BOs that are lookup at the start of exec doesn't need
to be instantiated as drm_gem_dma_object, as it doesn't benefit
from its attributes. So, simplify the code by replacing the array of
drm_gem_dma_object for an array of drm_gem_object in the struct
vc4_exec_info.

Suggested-by: Melissa Wen <mwen@igalia.com>
Signed-off-by: Maíra Canal <mcanal@igalia.com>
Reviewed-by: André Almeida <andrealmeid@igalia.com>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Signed-off-by: Maíra Canal <mairacanal@riseup.net>
Link: https://patchwork.freedesktop.org/patch/msgid/20230202111943.111757-2-mcanal@igalia.com