arm64: dts: zynqmp: make hw-ecc as the default ecc mode

Except for Linux no other component (i.e., u-boot, fsbl or BootRom) of the
software stack supports software ecc engine. So, make hw-ecc as the default
ecc mode.

Signed-off-by: Amit Kumar Mahapatra <amit.kumar-mahapatra@amd.com>
Signed-off-by: Michal Simek <michal.simek@amd.com>
Link: https://lore.kernel.org/r/f47b95616eb40d3a9908ca60df94ec6e873b071c.1697119098.git.michal.simek@amd.com