Fixes an obvious and nasty typo.

Fixes: a3b02a9c ("mux: minimal mux subsystem")
Signed-off-by: NKuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Signed-off-by: NPeter Rosin <peda@axentia.se>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>