mediatek: mt7622: remove '0x' prefix from pstore address in dts

mediatek: mt7622: remove '0x' prefix from pstore address in dts

Adresses of device tree nodes are typically noted without the '0x'
prefix. While having the '0x' prefix doesn't hurt when using Linux,
more recent versions of U-Boot will add a duplicate ramoops node as a
simple string compare is used to check if the node is already present.

Remove the '0x' prefix to avoid the kernel warning resulting from
U-Boot adding a dupplicate pstore/ramoops node.

See also https://lists.denx.de/pipermail/u-boot/2022-April/481810.html

Signed-off-by: Daniel Golle <daniel@makrotopia.org>