MAINAINTERS: Corrected Broadcom Northstar2 entry

While moving the Northstar 2 DTS into a dedicated directory, the
corresponding MAINTAINERS file entry was not updated accordingly, fix
that.

Fixes: 63a913c1 ("arm64: dts: move ns2 into northstar2 directory")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>

MAINTAINERS

@@ -2971,7 +2971,7 @@ N:	bcm585*
 N:	bcm586*
 N:	bcm88312
 N:	hr2
-F:	arch/arm64/boot/dts/broadcom/ns2*
+F:	arch/arm64/boot/dts/broadcom/northstar2/*
 F:	drivers/clk/bcm/clk-ns*
 F:	drivers/pinctrl/bcm/pinctrl-ns*