protobuf-c: update license information

[Peter: license is BSD-2c]
Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/protobuf-c/protobuf-c.mk

@@ -11,7 +11,8 @@ HOST_PROTOBUF_C_DEPENDENCIES = host-protobuf host-pkgconf
 PROTOBUF_C_MAKE = $(MAKE1)
 PROTOBUF_C_CONF_OPT = --disable-protoc
 PROTOBUF_C_INSTALL_STAGING = YES
-PROTOBUF_C_LICENSE = BSD-3c
+PROTOBUF_C_LICENSE = BSD-2c
+PROTOBUF_C_LICENSE_FILES = LICENSE
 PROTOBUF_C_AUTORECONF = YES
 HOST_PROTOBUF_C_AUTORECONF = YES