ARM: shmobile: Remove legacy board code for Armadillo-800 EVA

The Armadillo-800 EVA board is sufficiently supported by DT-based and
board-less R-Mobile A1 (r8a7740) multiplatform kernels, and board
staging code. Hence remove the legacy board code to reduce maintenance
effort.

Lacking areas are:
  - USB (it doesn't work in legacy, neither),
  - HDMI (it doesn't work in legacy, neither),
  - Camera (we don't care),
  - DMAC/IPMMU (no DT bindings are planned).

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>