MAINTAINERS: drop list entry for davinci

As davinci-linux-open-source@linux.davincidsp.com is now
shut and no more maintained by TI, drop this entry from
DAVINCI MACHINE SUPPORT and DAVINCI SERIES MEDIA DRIVER.

Signed-off-by: Lad, Prabhakar <prabhakar.csengg@gmail.com>
Cc: Kevin Hilman <khilman@deeprootsystems.com>
Cc: arm@kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Acked-by: Sekhar Nori <nsekhar@ti.com>
Signed-off-by: Kevin Hilman <khilman@linaro.org>