ARM: socfpga: dts: fix qspi node compatible

The QSPI flash node needs to have the required "jedec,spi-nor" in the
compatible string.

Fixes: 1df99da8

 ("ARM: dts: socfpga: Enable QSPI in Arria10 devkit")
Signed-off-by: Dinh Nguyen <dinguyen@kernel.org>