drm/sti: remove deprecated sti_vtac.c file

stih416 chip family is no more supported in Linux v4.9.
It is then useless to keep sti_vtac.c file since it not used at all for
the stih407/10 chip family supported by sti driver.

Signed-off-by: Vincent Abriou <vincent.abriou@st.com>
4 files changed