USB: gadget: functionfs: stale Makefile entry removed

Removed entry referencing g_eth_ffs.c file from Makefile.
The file never existed and the line was a leftover from a
developing process.
Signed-off-by: Michal Nazarewicz <m.nazarewicz@samsung.com>
Reported-by: Robert P. J. Day <rpjday@crashcourse.ca>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/gadget/Makefile

@@ -53,7 +53,6 @@ obj-$(CONFIG_USB_AUDIO)		+= g_audio.o
 obj-$(CONFIG_USB_ETH)		+= g_ether.o
 obj-$(CONFIG_USB_GADGETFS)	+= gadgetfs.o
 obj-$(CONFIG_USB_FUNCTIONFS)	+= g_ffs.o
-obj-$(CONFIG_USB_ETH_FUNCTIONFS)	+= g_eth_ffs.o
 obj-$(CONFIG_USB_FILE_STORAGE)	+= g_file_storage.o
 obj-$(CONFIG_USB_MASS_STORAGE)	+= g_mass_storage.o
 obj-$(CONFIG_USB_G_SERIAL)	+= g_serial.o