documentation: fpga: add bridge document to driver-api

Add a new document to driver-api/fpga that documents the
fpga bridge API and add it to driver-api/fpga/index.rst
Signed-off-by: Alan Tull <atull@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/driver-api/fpga/fpga-bridge.rst

+FPGA Bridge
+===========
+
+API to implement a new FPGA bridge
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. kernel-doc:: include/linux/fpga/fpga-bridge.h
+   :functions: fpga_bridge
+
+.. kernel-doc:: include/linux/fpga/fpga-bridge.h
+   :functions: fpga_bridge_ops
+
+.. kernel-doc:: drivers/fpga/fpga-bridge.c
+   :functions: fpga_bridge_create
+
+.. kernel-doc:: drivers/fpga/fpga-bridge.c
+   :functions: fpga_bridge_free
+
+.. kernel-doc:: drivers/fpga/fpga-bridge.c
+   :functions: fpga_bridge_register
+
+.. kernel-doc:: drivers/fpga/fpga-bridge.c
+   :functions: fpga_bridge_unregister
+
+API to control an FPGA bridge
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+You probably won't need these directly.  FPGA regions should handle this.
+
+.. kernel-doc:: drivers/fpga/fpga-bridge.c
+   :functions: of_fpga_bridge_get
+
+.. kernel-doc:: drivers/fpga/fpga-bridge.c
+   :functions: fpga_bridge_get
+
+.. kernel-doc:: drivers/fpga/fpga-bridge.c
+   :functions: fpga_bridge_put
+
+.. kernel-doc:: drivers/fpga/fpga-bridge.c
+   :functions: fpga_bridge_get_to_list
+
+.. kernel-doc:: drivers/fpga/fpga-bridge.c
+   :functions: of_fpga_bridge_get_to_list
+
+.. kernel-doc:: drivers/fpga/fpga-bridge.c
+   :functions: fpga_bridge_enable
+
+.. kernel-doc:: drivers/fpga/fpga-bridge.c
+   :functions: fpga_bridge_disable

Documentation/driver-api/fpga/index.rst

@@ -9,3 +9,4 @@ FPGA Subsystem
 
    intro
    fpga-mgr
+   fpga-bridge