ARM: shmobile: Remove legacy SoC code for R-Mobile A1

The last user of the R-Mobile A1 (r8a7740) legacy SoC code was the
Armadillo-800 EVA legacy board code, which has been removed.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
[horms: resolved trivial conflicts with v4.2-rc1]
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>