ipq40xx: GL-B1300: convert to new partitions layout

ipq40xx: GL-B1300: convert to new partitions layout

Alberto Bursi reported:
>The patch "ipq40xx: specify "firmware" partition format for GL.iNet GL-B1300"
>prevents boot on my B1300. I compiled from latest sources.

The GL-B1300 was using the discouraged direct subnodes method to declare
the partitions on the flash.

|The partition table should be a subnode of the flash node and should be named
|'partitions'. This node should have the following property:
|- compatible : (required) must be "fixed-partitions"
|Partitions are then defined in subnodes of the partitions node.
|
|For backwards compatibility partitions as direct subnodes of the flash device are
|supported. This use is discouraged.
|NOTE: also for backwards compatibility, direct subnodes that have a compatible
|string are not considered partitions, as they may be used for other bindings.
<https://www.kernel.org/doc/Documentation/devicetree/bindings/mtd/partition.txt>

Hence, this patch converts the device to the "partitions" layout.

Fixes: 1cbe457cf94 ("ipq40xx: specify "firmware" partition format for GL.iNet GL-B1300")
Reported-by: Alberto Bursi <bobafetthotmail@gmail.com>
Signed-off-by: Christian Lamparter <chunkeey@gmail.com>