tun: rename FD_TYPES__TUN to FD_TYPES__TUNF

We have two global enums with the member TUN. The first one is in fdinfo.proto and the
second one is in netdev.proto. protoc complains about having TUN in 2 global enums because
of the enum rules for C++(even though we're compiling .proto files for python).
So lets rename TUN into TUNF to avoid that conflict.
Signed-off-by: Ruslan Kuprieiev <kupruser@gmail.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

protobuf/fdinfo.proto

@@ -14,7 +14,7 @@ enum fd_types {
 	FANOTIFY	= 12;
 	NETLINKSK	= 13;
 	NS		= 14;
-	TUN		= 15;
+	TUNF		= 15;
 	EXT		= 16;
 	TIMERFD		= 17;
 }

tun.c

@@ -311,7 +311,7 @@ static int dump_tunfile(int lfd, u32 id, const struct fd_parms *p)
 }
 
 const struct fdtype_ops tunfile_dump_ops = {
-	.type = FD_TYPES__TUN,
+	.type = FD_TYPES__TUNF,
 	.dump = dump_tunfile,
 };
 
@@ -376,7 +376,7 @@ err:
 }
 
 static struct file_desc_ops tunfile_desc_ops = {
-	.type = FD_TYPES__TUN,
+	.type = FD_TYPES__TUNF,
 	.open = tunfile_open,
 };