ARM: dts: imx6qdl-kontron-samx6i: fix spi-flash compatible

Drop the "winbond,w25q16dw" compatible since it causes to set the
MODALIAS to w25q16dw which is not specified within spi-nor id table.
Fix this by use the common "jedec,spi-nor" compatible.

Fixes: 21252127 ("ARM: dts: imx6qdl-kontron-samx6i: add Kontron SMARC SoM Support")
Signed-off-by: Marco Felsch <m.felsch@pengutronix.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>