This quiets the following sparse noise:

warning: symbol 'exofs_sync_fs' was not declared. Should it be static?
warning: symbol 'exofs_free_sbi' was not declared. Should it be static?
warning: symbol 'exofs_get_parent' was not declared. Should it be static?
Signed-off-by: NH Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: NBoaz Harrosh <bharrosh@panasas.com>