arm: dts: Switch Apple silicon devices to dts/upstream

arm: dts: Switch Apple silicon devices to dts/upstream

The device tree on Apple silicon devices is passed from a previous
bootloader stage. The bootloader fills in dynamic information so
u-boot can not use its own device tree.
As documented in doc/board/apple/m1.rst it is possible to build boot
bundles (bootloader + device tree + gzipped u-boot binary). These are
useful for testing.
Instead of using u-boot's own device trees for M1 (t8103) devices use
upstream device trees from dts/upstream/src/arm64/apple. The u-boot
device trees have not seen updates since 2022. The upstream linux device
trees have feature parity for the M1 devices. In addition linux has
device trees for M1 Pro/Max/Ultra, M2 and M2 Pro/Max/Ultra devices.
Keep t8103-j274 as default device tree to avoid further updates.

Signed-off-by: Janne Grunau <j@jannau.net>
Acked-by: Mark Kettenis <kettenis@openbsd.org>