[PATCH] net/9p/usbg: Fix build error

[Jinjie Ruan]

When CONFIG_NET_9P_USBG=y but CONFIG_USB_LIBCOMPOSITE=m and
CONFIG_CONFIGFS_FS=m, the following build error occurs:

	riscv64-unknown-linux-gnu-ld: net/9p/trans_usbg.o: in function `usb9pfs_free_func':
	trans_usbg.c:(.text+0x124): undefined reference to `usb_free_all_descriptors'
	riscv64-unknown-linux-gnu-ld: net/9p/trans_usbg.o: in function `usb9pfs_rx_complete':
	trans_usbg.c:(.text+0x2d8): undefined reference to `usb_interface_id'
	riscv64-unknown-linux-gnu-ld: trans_usbg.c:(.text+0x2f6): undefined reference to `usb_string_id'
	riscv64-unknown-linux-gnu-ld: net/9p/trans_usbg.o: in function `usb9pfs_func_bind':
	trans_usbg.c:(.text+0x31c): undefined reference to `usb_ep_autoconfig'
	riscv64-unknown-linux-gnu-ld: trans_usbg.c:(.text+0x336): undefined reference to `usb_ep_autoconfig'
	riscv64-unknown-linux-gnu-ld: trans_usbg.c:(.text+0x378): undefined reference to `usb_assign_descriptors'
	riscv64-unknown-linux-gnu-ld: net/9p/trans_usbg.o: in function `f_usb9pfs_opts_buflen_store':
	trans_usbg.c:(.text+0x49e): undefined reference to `usb_put_function_instance'
	riscv64-unknown-linux-gnu-ld: net/9p/trans_usbg.o: in function `usb9pfs_alloc_instance':
	trans_usbg.c:(.text+0x5fe): undefined reference to `config_group_init_type_name'
	riscv64-unknown-linux-gnu-ld: net/9p/trans_usbg.o: in function `usb9pfs_alloc':
	trans_usbg.c:(.text+0x7aa): undefined reference to `config_ep_by_speed'
	riscv64-unknown-linux-gnu-ld: trans_usbg.c:(.text+0x7ea): undefined reference to `config_ep_by_speed'
	riscv64-unknown-linux-gnu-ld: net/9p/trans_usbg.o: in function `usb9pfs_set_alt':
	trans_usbg.c:(.text+0x828): undefined reference to `alloc_ep_req'
	riscv64-unknown-linux-gnu-ld: net/9p/trans_usbg.o: in function `usb9pfs_modexit':
	trans_usbg.c:(.exit.text+0x10): undefined reference to `usb_function_unregister'
	riscv64-unknown-linux-gnu-ld: net/9p/trans_usbg.o: in function `usb9pfs_modinit':
	trans_usbg.c:(.init.text+0x1e): undefined reference to `usb_function_register'

Select the config for NET_9P_USBG to fix it.

Fixes: a3be076dc174 ("net/9p/usbg: Add new usb gadget function transport")
Signed-off-by: Jinjie Ruan <ruanjinjie at huawei.com>
---
 net/9p/Kconfig | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/9p/Kconfig b/net/9p/Kconfig
index 63f988f0c9e8..ee967fd25312 100644
--- a/net/9p/Kconfig
+++ b/net/9p/Kconfig
@@ -43,6 +43,8 @@ config NET_9P_XEN
 config NET_9P_USBG
 	bool "9P USB Gadget Transport"
 	depends on USB_GADGET=y || USB_GADGET=NET_9P
+	select CONFIGFS_FS
+	select USB_LIBCOMPOSITE
 	help
 	  This builds support for a transport for 9pfs over
 	  usb gadget.
-- 
2.34.1