ARM: dts: mstar: Mark timer with arm,cpu-registers-not-fw-configured

The vendor u-boot does not configure the arch timer correctly on
MStar, let Linux do it.

Signed-off-by: Romain Perier <romain.perier@gmail.com>
Signed-off-by: Daniel Palmer <daniel@0x0f.com>
Link: https://lore.kernel.org/linux-arm-kernel/20210923170747.5786-2-romain.perier@gmail.com