reset: zynqmp: Add reset controller for ZynqMP SoC

Add firmware based reset controller for Xilinx ZynqMP SoC to let other
drivers to call reset functions. Driver is only tested on Xilinx ZynqMP but
support for Xilinx Versal can be simply added. That's why reset_id and
nr_reset are assigned in probe folder.
Driver is inpired by driver from Linux kernel.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
diff --git a/MAINTAINERS b/MAINTAINERS
index 483a4584..868d4e1 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -600,6 +600,7 @@
 F:	drivers/net/phy/xilinx_phy.c
 F:	drivers/net/zynq_gem.c
 F:	drivers/serial/serial_zynq.c
+F:	drivers/reset/reset-zynqmp.c
 F:	drivers/rtc/zynqmp_rtc.c
 F:	drivers/spi/zynq_qspi.c
 F:	drivers/spi/zynq_spi.c