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 <[e-mail]>
Closes: https://lore.kernel.org/oe-kbuild-all/[e-mail]/
Signed-off-by: Christian Marangi <[e-mail]>
Reviewed-by: Florian Fainelli <[e-mail]>
Signed-off-by: Thomas Bogendoerfer <[e-mail]>

arch/mips/boot/dts/brcm/bcm6358.dtsi

···
 		#size-cells = <0>;
 
 		mips-hpt-frequency = <150000000>;
+		brcm,bmips-cbr-reg = <0xff400000>;
 
 		cpu@0 {
 			compatible = "brcm,bmips4350";

arch/mips/boot/dts/brcm/bcm6368.dtsi

···
 		#size-cells = <0>;
 
 		mips-hpt-frequency = <200000000>;
+		brcm,bmips-cbr-reg = <0xff400000>;
 
 		cpu@0 {
 			compatible = "brcm,bmips4350";