usbip: remove no longer necessary udev hack

It's not only unnecessary, it interferes with libudev-zero.

Signed-off-by: Rosen Penev <rosenp@gmail.com>

net/usbip/Makefile

@@ -9,8 +9,8 @@ include $(TOPDIR)/rules.mk
 include $(INCLUDE_DIR)/kernel.mk
 
 PKG_NAME:=usbip
-PKG_RELEASE:=11
-PKG_LICENSE:=GPL-2.0
+PKG_RELEASE:=12
+PKG_LICENSE:=GPL-2.0-only
 
 # Since kernel 2.6.39.1 userspace tools are inside the kernel tree
 # Package Automatic match version in kernel
@@ -70,8 +70,6 @@ endef
 CONFIGURE_PATH:=.
 MAKE_PATH:=.
 LIBTOOL_PATHS:=.
-MAKE_FLAGS+=CFLAGS='-Dudev_device_get_devpath\(x\)=udev_device_get_syspath\(x\)+strlen\(\"/sys\"\) \
-	-DSIGCLD=SIGCHLD'
 CONFIGURE_ARGS+= --disable-silent-rules
 
 define Build/Configure