video: move SH_MIPI_DSI/SH_LCD_MIPI_DSI to the top of menu

Kconfig entries SH_MIPI_DSI and SH_LCD_MIPI_DSI while being invisible to
the user, broke the FrameBuffer menu (at least in menuconfig), as they
aren't depending on respective menuconfig item (FB). In result several
items got moved to the main "Graphics support" menu. Move these two
problematic items to the top of drivers/video/Kbuild to restore nice
display of FB menu.

Signed-off-by: Dmitry Eremin-Solenikov <dbaryshkov@gmail.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>