arm64: dts: ls1046a: Add QSPI node for ls1046afrwy

This board has a single 64MB mt25qu512a flash.
QUAD I/O read and single I/O write is tested.

Signed-off-by: Kuldeep Singh <kuldeep.singh@nxp.com>
Signed-off-by: Ashish Kumar <Ashish.Kumar@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>