MAINTAINERS: Update Broadcom iProc entry with Stingray

Update the MAINTAINERS file to cover the "stingray" pattern and a few
files under arch/arm64/boot/dts/broadcom/* as well as the clock driver
and binding.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
diff --git a/MAINTAINERS b/MAINTAINERS
index 67b014e..c78feb0 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -2971,9 +2971,13 @@
 N:	bcm586*
 N:	bcm88312
 N:	hr2
+N:	stingray
 F:	arch/arm64/boot/dts/broadcom/northstar2/*
+F:	arch/arm64/boot/dts/broadcom/stingray/*
 F:	drivers/clk/bcm/clk-ns*
+F:	drivers/clk/bcm/clk-sr*
 F:	drivers/pinctrl/bcm/pinctrl-ns*
+F:	include/dt-bindings/clock/bcm-sr*
 
 BROADCOM KONA GPIO DRIVER
 M:	Ray Jui <rjui@broadcom.com>