ARM: dts: am335x-myirtech: Update NAND default partition table layout

This patch replaces the legacy partition table layout with a modern style.
As an additional change, we are reserving space for three backup MLO entries
and increasing space for the main bootloader.

Signed-off-by: Alexander Shiyan <eagle.alexander923@gmail.com>
Message-Id: <20220427081914.6773-2-eagle.alexander923@gmail.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>