arm64: dts: fsl: ls1046a: disable the flash controller by default

Set the Integrated Flash Controller status to disabled so each board has
the option to enable it. All the existing users have status = "okay" so
there is no functional change.

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>