docs: infrastructure.rst: don't include firmware kernel-doc

Those are already documented at:

	Documentation/driver-api/firmware/request_firmware.rst

Including it twice is causing lots of warnings:

	./Documentation/driver-api/infrastructure.rst: WARNING: Duplicate C declaration, also defined in 'driver-api/firmware/request_firmware'.
	Declaration is 'request_firmware'.
	./Documentation/driver-api/infrastructure.rst: WARNING: Duplicate C declaration, also defined in 'driver-api/firmware/request_firmware'.
	Declaration is 'firmware_request_nowarn'.
	./Documentation/driver-api/infrastructure.rst: WARNING: Duplicate C declaration, also defined in 'driver-api/firmware/request_firmware'.
	Declaration is 'request_firmware_direct'.
	./Documentation/driver-api/infrastructure.rst: WARNING: Duplicate C declaration, also defined in 'driver-api/firmware/request_firmware'.
	Declaration is 'firmware_request_platform'.
	./Documentation/driver-api/infrastructure.rst: WARNING: Duplicate C declaration, also defined in 'driver-api/firmware/request_firmware'.
	Declaration is 'firmware_request_cache'.
	./Documentation/driver-api/infrastructure.rst: WARNING: Duplicate C declaration, also defined in 'driver-api/firmware/request_firmware'.
	Declaration is 'request_firmware_into_buf'.
	./Documentation/driver-api/infrastructure.rst: WARNING: Duplicate C declaration, also defined in 'driver-api/firmware/request_firmware'.
	Declaration is 'request_firmware_nowait'.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

Documentation/driver-api/infrastructure.rst

@@ -28,9 +28,6 @@ Device Drivers Base
 .. kernel-doc:: drivers/base/node.c
    :internal:
 
-.. kernel-doc:: drivers/base/firmware_loader/main.c
-   :export:
-
 .. kernel-doc:: drivers/base/transport_class.c
    :export: