firmware: zynqmp: create firmware header

New firmware header to place firmware specific macro and function
declarations. The patch also moves the macros defining PM operations as
well as some helper macros.

Signed-off-by: Ibai Erkiaga <ibai.erkiaga-elorza@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
diff --git a/MAINTAINERS b/MAINTAINERS
index 6af9816..2ef2976 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -461,6 +461,7 @@
 F:	drivers/usb/host/ehci-zynq.c
 F:	drivers/watchdog/cdns_wdt.c
 F:	include/zynqmppl.h
+F:	include/zynqmp_firmware.h
 F:	tools/zynqmp*
 N:	ultra96
 N:	zynqmp