Ensure device and driver lifetime from of_fpga_mgr_get() to
fpga_mgr_put().

* Don't put_device() in of_fpga_mgr_get, do it in fpga_mgr_put().
  (still do put_device if there is an error).
* Do module_get on the low level driver.
* Don't need to module_get(THIS_MODULE) since we won't be allowed
  to unload the fpga manager core without unloading low level
  driver first.
* Remove unnedessary null check for node pointer.
Signed-off-by: NAlan Tull <atull@opensource.altera.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

API to support programming FPGA's.

The following functions are exported as GPL:
* fpga_mgr_buf_load
   Load fpga from image in buffer

* fpga_mgr_firmware_load
   Request firmware and load it to the FPGA.

* fpga_mgr_register
* fpga_mgr_unregister
   FPGA device drivers can be added by calling
   fpga_mgr_register() to register a set of
   fpga_manager_ops to do device specific stuff.

* of_fpga_mgr_get
* fpga_mgr_put
   Get/put a reference to a fpga manager.

The following sysfs files are created:
* /sys/class/fpga_manager/<fpga>/name
  Name of low level driver.

* /sys/class/fpga_manager/<fpga>/state
  State of fpga manager
Signed-off-by: NAlan Tull <atull@opensource.altera.com>
Acked-by: NMichal Simek <michal.simek@xilinx.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>