riscv: dts: starfive: fix NOR flash reserved-data partition size

riscv: dts: starfive: fix NOR flash reserved-data partition size

The Starfive VisionFive 2 has a 16MiB NOR flash, while the reserved-data
partition is declared starting at address 0x600000 with a size of
0x1000000. This causes the kernel to output the following warning:

[   22.156589] mtd: partition "reserved-data" extends beyond the end of device "13010000.spi.0" -- size truncated to 0xa00000

It seems to be a confusion between the size of the partition and the end
address. Fix that by specifying the right size.

Fixes: 8384087a4223 ("riscv: dts: starfive: Add QSPI controller node for StarFive JH7110 SoC")
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
Reviewed-by: Emil Renner Berthing <emil.renner.berthing@canonical.com>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>