makedevs: add license information

[Thomas: change license to be GPLv2. The header of makedevs.c is a bit
unclear, as it mentions both the GPL and LGPL. But since the code
seems to originally be coming from Busybox, assuming GPLv2 is the
safest option.]

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/makedevs/makedevs.mk

@@ -9,6 +9,7 @@ MAKEDEVS_SOURCE =
 HOST_MAKEDEVS_SOURCE =
 
 MAKEDEVS_VERSION = buildroot-$(BR2_VERSION)
+MAKEDEVS_LICENSE = GPLv2
 
 define MAKEDEVS_BUILD_CMDS
 	$(TARGET_CC) $(TARGET_CFLAGS) $(TARGET_LDFLAGS) \