fsi: fsi_master_class can be static

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Fixes: 0604d53d4da8 ("fsi: Add fsi-master class")
Signed-off-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Joel Stanley <joel@jms.id.au>
Link: https://lore.kernel.org/r/20191108051945.7109-7-joel@jms.id.au


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>