soc: renesas: Enable ARM_ERRATA_814220 for affected Cortex-A7

ARM Erratum 814220 affects Cortex-A7 revisions r0p2-r0p5.

Automatically enable support code to mitigate the erratum when compiling
a kernel for any of the affected Renesas SoCs:
  - R-Mobile APE6: r0p2,
  - RZ/G1E: r0p5,
  - RZ/G1C: r0p5,
  - R-Car H2: r0p3,
  - R-Car E2: r0p5,
  - RZ/N1: r0p5.

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