scsi: core: Declare 'scsi_scan_type' static

'scsi_scan_type' is only used in one source file. Hence declare it static.

Link: https://lore.kernel.org/r/20211129194609.3466071-3-bvanassche@acm.org
Fixes: a19a93e4 ("scsi: core: pm: Rely on the device driver core for async power management")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/scsi_scan.c

@@ -97,7 +97,7 @@ MODULE_PARM_DESC(max_luns,
 #define SCSI_SCAN_TYPE_DEFAULT "sync"
 #endif
 
-char scsi_scan_type[7] = SCSI_SCAN_TYPE_DEFAULT;
+static char scsi_scan_type[7] = SCSI_SCAN_TYPE_DEFAULT;
 
 module_param_string(scan, scsi_scan_type, sizeof(scsi_scan_type),
 		    S_IRUGO|S_IWUSR);