Fix ene_ub6250 build: it uses usb_storage driver interfaces, so it
should depend on USB_STORAGE.

ene_ub6250.c:(.text+0x14ff19): undefined reference to `usb_stor_reset_resume'
ene_ub6250.c:(.text+0x14ffb1): undefined reference to `usb_stor_bulk_transfer_buf'
ene_ub6250.c:(.text+0x14ffdd): undefined reference to `usb_stor_bulk_srb'
ene_ub6250.c:(.text+0x14fff1): undefined reference to `usb_stor_bulk_transfer_sg'
ene_ub6250.c:(.text+0x1503dd): undefined reference to `usb_stor_set_xfer_buf'
ene_ub6250.c:(.text+0x15048e): undefined reference to `usb_stor_access_xfer_buf'
ene_ub6250.c:(.text+0x150723): undefined reference to `usb_stor_probe1'
ene_ub6250.c:(.text+0x150795): undefined reference to `usb_stor_probe2'
ene_ub6250.c:(.text+0x1507af): undefined reference to `usb_stor_disconnect'
drivers/built-in.o:(.data+0x10224): undefined reference to `usb_stor_suspend'
drivers/built-in.o:(.data+0x10230): undefined reference to `usb_stor_pre_reset'
drivers/built-in.o:(.data+0x10234): undefined reference to `usb_stor_post_reset'
Signed-off-by: NRandy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>