staging: usbip: userspace: fix build breakage in doc directory

File doc/usbip_bind_driver.8 does not exist any more but it is
listed in dist_man_MANS. This breaks the build of the userspace.
Remove the file from the list.
Signed-off-by: Ilija Hadzic <ihadzic@research.bell-labs.com>
Acked-by: David Chang <dchang@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/usbip/userspace/Makefile.am

@@ -3,4 +3,4 @@ includedir = @includedir@/usbip
 include_HEADERS := $(addprefix libsrc/, \
 		     usbip_common.h vhci_driver.h usbip_host_driver.h)
 
-dist_man_MANS := $(addprefix doc/, usbip.8 usbipd.8 usbip_bind_driver.8)
+dist_man_MANS := $(addprefix doc/, usbip.8 usbipd.8)