ARM: dts: ls1021a: Rename node name nor to flash

ARM: dts: ls1021a: Rename node name nor to flash

Rename node name nor to flash to fix below CHECK_DTBS warnings:

arch/arm/boot/dts/nxp/ls/ls1021a-twr.dtb: memory-controller@1530000 (fsl,ifc): 'nor@0,0' does not match any of the regexes: '(flash|fpga|board-control|cpld)@[a-f0-9]+(,[a-f0-9]+)+$', '^nand@[a-f0-9]+(,[a-f0-9]+)+$', '^pinctrl-[0-9]+$'

Signed-off-by: Frank Li <Frank.Li@nxp.com>
Reviewed-by: Alexander Stein <alexander.stein@ew.tq-group.com>
Reviewed-by: Peng Fan <peng.fan@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>