fbdev: Remove unused SH-Mobile HDMI driver

As of commit 44d88c75 ("ARM: shmobile: Remove legacy SoC code
for R-Mobile A1"), the SH-Mobile HDMI driver is no longer used.
In theory it could still be used on R-Mobile A1 SoCs, but that requires
adding DT support to the driver, which is not planned.

Remove the driver, it can be resurrected from git history when needed.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>