ARM: dts: ls1021a: Remove unused properties from QSPI node

After switching to the new FSL QSPI driver the properties
'fsl,qspi-has-second-chip' and 'big-endian' are not used anymore.

The driver now uses the 'reg' property to determine the bus and
the chipselect. The endianness is selected by the driver depending
on which SoC is used.

Signed-off-by: Frieder Schrempf <frieder.schrempf@kontron.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>