drm/msm/adreno: Add a modparam to skip GPU

drm/msm/adreno: Add a modparam to skip GPU

During bringup of a new GPU support, it is convenient to have knob to
quickly disable GPU, but keep the display support. This helps to
fallback to 'kms_swrast' in case of bootup issues due to GPU. Add a
modparam to support this.

Signed-off-by: Akhil P Oommen <akhilpo@oss.qualcomm.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Patchwork: https://patchwork.freedesktop.org/patch/672262/
Link: https://lore.kernel.org/r/20250902-assorted-sept-1-v1-3-f3ec9baed513@oss.qualcomm.com
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>