staging: board: Remove Armadillo-800-EVA board staging code

Since commits 1399ebac ("drm: renesas: shmobile: Add DT
support"), 138588e9 ("ARM: dts: renesas: r8a7740: Add LCDC
nodes"), and c9a0ed13

 ("ARM: dts: renesas: armadillo800eva: Add
LCD panel"), there is no longer any use for the Atmark Techno
Armadillo-800-EVA board staging code.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Link: https://lore.kernel.org/r/6d51e06a8586997b31eecead55a369f01c5696a7.1705932585.git.geert+renesas@glider.be
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>