scsci/sg.h: fix usage of undefined macro HZ

this macro is 100 on all archs, at least in userspace, according
to kernel headers.

include/scsi/sg.h

@@ -52,7 +52,7 @@
 #define SG_SET_COMMAND_Q 0x2271
 #define SG_SET_DEBUG 0x227e
 #define SG_NEXT_CMD_LEN 0x2283
-#define SG_DEFAULT_TIMEOUT (60*HZ)
+#define SG_DEFAULT_TIMEOUT (60*100) /* 60*HZ */
 #define SG_DEF_COMMAND_Q 0
 #define SG_DEF_UNDERRUN_FLAG 0