drm/panthor: Label all kernel BO's

Kernel BO's aren't exposed to UM, so labelling them is the responsibility
of the driver itself. This kind of tagging will prove useful in further
commits when want to expose these objects through DebugFS.

Expand panthor_kernel_bo_create() interface to take a NUL-terminated
string. No bounds checking is done because all label strings are given
as statically-allocated literals, but if a more complex kernel BO naming
scheme with explicit memory allocation and formatting was desired in the
future, this would have to change.

Signed-off-by: Adrián Larumbe <adrian.larumbe@collabora.com>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: Liviu Dudau <liviu.dudau@arm.com>
Reviewed-by: Steven Price <steven.price@arm.com>
Link: https://lore.kernel.org/r/20250423021238.1639175-4-adrian.larumbe@collabora.com


Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>