drm/lima: allocate unique id per drm_file

To track if fds are pointing to the same execution context and export
the expected information to fdinfo, similar to what is done in other
drivers.

Signed-off-by: Erico Nunes <nunes.erico@gmail.com>
Signed-off-by: Qiang Yu <yuq825@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230312233052.21095-3-nunes.erico@gmail.com