dt-bindings: timer: Add SC5xx Timer bindings

Add devicetree schema for the timer peripheral on Analog Devices SC5xx
series SoCs.

Signed-off-by: Oliver Gaskell <Oliver.Gaskell@analog.com>
diff --git a/MAINTAINERS b/MAINTAINERS
index c196368..0bc7f2f 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -609,6 +609,7 @@
 F:	arch/arm/mach-sc5xx/
 F:	doc/device-tree-bindings/arm/adi/adi,sc5xx.yaml
 F:	doc/device-tree-bindings/clock/adi,sc5xx-clocks.yaml
+F:	doc/device-tree-bindings/timer/adi,sc5xx-gptimer.yaml
 F:	drivers/clk/adi/
 F:	drivers/serial/serial_adi_uart4.c
 F:	drivers/timer/adi_sc5xx_timer.c