mips: bmips: bcm6358/6368: define required brcm,bmips-cbr-reg

For the bcm6358/6368 SoC the brcm,bmips-cbr-reg due to bootloader
misconfiguration or HW bug from running the system from TP1.

A workaround is now present to handle broken system that suffer from
this bug hence add the now required property.

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202409251520.pE12GzHd-lkp@intel.com/


Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>