qualcommax: ipq50xx: remove disabled partitions node

qualcommax: ipq50xx: remove disabled partitions node

Although the bootloader tries to 'fixup' the qpic nand node, it actually
can't find it as the node was renamed to spi based on the new driver
architecture. The added benefit is that it also silences build warning:

Warning (spi_bus_reg): /soc@0/spi@79b0000/partitions: missing or empty reg property

Signed-off-by: George Moussalem <george.moussalem@outlook.com>
---
Node rename:

old node name: qpic-nand@79b0000
new node name: spi@79b0000

Bootloader logs:

   Booting using the fdt blob at 0x44d3fc78
   Uncompressing Kernel Image ... OK
   Loading Device Tree to 4a3f6000, end 4a3ff805 ... OK
fdt_fixup_qpic: QPIC: unable to find node '/soc/qpic-nand@79b0000'
parse_fdt_fixup: unable to find node '/soc/qpic-nand@79b0000/'
Link: https://github.com/openwrt/openwrt/pull/20982
Signed-off-by: Robert Marko <robimarko@gmail.com>