ARM Erratum 754322 affects Cortex-A9 revisions r2p* and r3p*.

Automatically enable support code to mitigate the erratum when compiling
a kernel for any of the affected Renesas SoCs:
  - RZ/A1: r3p0,
  - R-Mobile A1: r2p4,
  - R-Car M1A: r2p2-00rel0,
  - R-Car H1: r3p0,
  - SH-Mobile AG5: r2p2.

EMMA Mobile EV2 (r1p3) and RZ/A2 (r4p1) are not affected.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>