drm/imagination: Fixed oops when misusing ioctl CREATE_HWRT_DATASET

While writing the matching IGT suite I discovered that it's possible to
cause a kernel oops when using DRM_IOCTL_PVR_CREATE_HWRT_DATASET when
the call to hwrt_init_common_fw_structure() fails.

Use an unwind-type error path to avoid cleaning up the object using the
the release function before it is fully resolved.

Signed-off-by: Donald Robson <donald.robson@imgtec.com>
Signed-off-by: Maxime Ripard <mripard@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20231208163019.95913-1-donald.robson@imgtec.com

drm/imagination: Implement free list and HWRT create and destroy ioctls

Implement ioctls to create and destroy free lists and HWRT datasets. Free
lists are used for GPU-side memory allocation during geometry processing.
HWRT datasets are the FW-side structures representing render targets.

Changes since v8:
- Corrected license identifiers

Changes since v6:
- Fix out-of-bounds shift in get_cr_multisamplectl_val()

Changes since v4:
- Remove use of drm_gem_shmem_get_pages()

Changes since v3:
- Support free list grow requests from FW
- Use drm_dev_{enter,exit}

Co-developed-by: Boris Brezillon <boris.brezillon@collabora.com>
Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Co-developed-by: Donald Robson <donald.robson@imgtec.com>
Signed-off-by: Donald Robson <donald.robson@imgtec.com>
Signed-off-by: Sarah Walker <sarah.walker@imgtec.com>
Link: https://lore.kernel.org/r/919358c5887a7628da588c455a5bb7e3ea4b47ae.1700668843.git.donald.robson@imgtec.com
Signed-off-by: Maxime Ripard <mripard@kernel.org>