fpga: litex: Update for "Use standard dev_release for class driver"

[geertu]

As of commit 4ba0b2c ("fpga: mgr: Use standard dev_release for
class driver"):

drivers/fpga/litex-fpga.c: In function ‘litex_fpga_probe’:
drivers/fpga/litex-fpga.c:168:8: error: implicit declaration of function ‘devm_fpga_mgr_create’; did you mean ‘devm_fpga_mgr_register’? [-Werror=implicit-function-declaration]
  168 |  mgr = devm_fpga_mgr_create(&pdev->dev,
  |        ^~~~~~~~~~~~~~~~~~~~
  |        devm_fpga_mgr_register
drivers/fpga/litex-fpga.c:168:6: warning: assignment to ‘struct fpga_manager *’ from ‘int’ makes pointer from integer without a cast [-Wint-conversion]
  168 |  mgr = devm_fpga_mgr_create(&pdev->dev,
  |      ^
drivers/fpga/litex-fpga.c:175:27: error: passing argument 1 of ‘fpga_mgr_register’ from incompatible pointer type [-Werror=incompatible-pointer-types]
  175 |  return fpga_mgr_register(mgr);
  |                           ^~~
  |                           |
  |                           struct fpga_manager *
In file included from drivers/fpga/litex-fpga.c:21:
include/linux/fpga/fpga-mgr.h:217:1: note: expected ‘struct device *’ but argument is of type ‘struct fpga_manager *’
  217 | fpga_mgr_register(struct device *parent, const char *name,
  | ^~~~~~~~~~~~~~~~~
drivers/fpga/litex-fpga.c:175:9: error: too few arguments to function ‘fpga_mgr_register’
  175 |  return fpga_mgr_register(mgr);
  |         ^~~~~~~~~~~~~~~~~
In file included from drivers/fpga/litex-fpga.c:21:
include/linux/fpga/fpga-mgr.h:217:1: note: declared here
  217 | fpga_mgr_register(struct device *parent, const char *name,
  | ^~~~~~~~~~~~~~~~~
drivers/fpga/litex-fpga.c:176:1: error: control reaches end of non-void function [-Werror=return-type]
  176 | }
  | ^

Update the LiteX ICAPBitstream FPGA Manager driver accordingly.

Fixes: 0b11c29 ("LiteX: driver for ICAPBitstream fpga manager")
Signed-off-by: Geert Uytterhoeven geert@linux-m68k.org

Compile-tested only.
Feel free to fold into the original commit.

[geertu]

@rw1nkler

[gsomlo]

applied, thanks!