configs: ls1046: Update mtd-id for QSPI nor in mtdparts variable

Update mtd-id for QSPI nor due to change introduced in mtd/spi in
linux 5.0. commit 84d043185dbe
  ("spi: Add a driver for the Freescale/NXP QuadSPI controller")

This modification is only for linux kernel version >= 5.0. To use
bootargs for kernel < 5.0, use the following bootargs
CONFIG_BOOTARGS="console=ttyS0,115200 root=/dev/ram0
earlycon=uart8250,mmio,0x21c0500
mtdparts=1550000.quadspi:2m(uboot),14m(free)"

CONFIG_MTDPARTS_DEFAULT="mtdparts=1550000.quadspi:2m(uboot),14m(free)"

Signed-off-by: Kuldeep Singh <kuldeep.singh@nxp.com>
Reviewed-by: Prabhakar Kushwaha <prabhakar.kushwaha@nxp.com>