ARM: imx: novena: Move defconfig bits to arch Kconfig

Just move the defconfig entries which are required into the Novena
entry in arch Kconfig, no functional change.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Fabio Estevam <fabio.estevam@nxp.com>
Cc: Stefano Babic <sbabic@denx.de>
Cc: Vagrant Cascadian <vagrant@debian.org>