MAINTAINERS: Add entry for BM1880 pinctrl

Add MAINTAINERS entry for Bitmain BM1880 SoC pinctrl.
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

MAINTAINERS

@@ -1416,7 +1416,9 @@ M:	Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
 L:	linux-arm-kernel@lists.infradead.org (moderated for non-subscribers)
 S:	Maintained
 F:	arch/arm64/boot/dts/bitmain/
+F:	drivers/pinctrl/pinctrl-bm1880.c
 F:	Documentation/devicetree/bindings/arm/bitmain.yaml
+F:	Documentation/devicetree/bindings/pinctrl/bitmain,bm1880-pinctrl.txt
 
 ARM/CALXEDA HIGHBANK ARCHITECTURE
 M:	Rob Herring <robh@kernel.org>