Turns out when introducing the eMMC version the gpmi node required for
NAND flash support got enabled exclusively on Colibri iMX7D 512MB.

Fixes: f928a4a3 ("ARM: dts: imx7: add Toradex Colibri iMX7D 1GB (eMMC) support")
Signed-off-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>