MAINTAINERS: add entry for tidss

Add entry for tidss DRM driver.

Version history:

v2: no change

v3: - Move tidss entry after omapdrm
    - Add "T:     git git://anongit.freedesktop.org/drm/drm-misc

"

v4: no change

v5: no change

v6: no change

v7: no change

v8: - Add Reviewed-by: Benoit Parrot <bparrot@ti.com>

v9: - Add Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

Signed-off-by: Jyri Sarha <jsarha@ti.com>
Reviewed-by: Benoit Parrot <bparrot@ti.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Link: https://patchwork.freedesktop.org/patch/msgid/c22f7aa31af09cd4adcca6b1a6b0721d9429f055.1580129724.git.jsarha@ti.com