ARM: at91: sama5: Update defconfig

Enable CGROUPS support, so we can boot userspace that uses systemd on
top of kernel configured using this defconfig. The systemd userspace
depends on cgroups and without them, it dies in mysterious ways.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Ludovic Desroches <ludovic.desroches@atmel.com>
Cc: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>