ARM: shmobile: Add the R9A06G032 SMP enabler driver

The Renesas R9A06G032 second CA7 is parked in a ROM pen at boot time, it
equires a special enable method to get it started.

Signed-off-by: Michel Pollet <michel.pollet@bp.renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>