Documentation: freefall: simplify pathnames

Copying to local variable is actually not neccessary, if all we need
to do is snprintf(). This also removes problem where devname could be
missing zero termination.
Reported-by: NRickard Strandqvist <rickard_strandqvist@spectrumdigital.se>
Signed-off-by: NPavel Machek <pavel@ucw.cz>
Signed-off-by: NRandy Dunlap <rdunlap@infradead.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Documentation/laptops/freefall.c

@@ -29,16 +29,12 @@ static const char app_name[] = "FREE FALL";
 
 static int set_unload_heads_path(char *device)
 {
-	char devname[64];
-
 	if (strlen(device) <= 5 || strncmp(device, "/dev/", 5) != 0)
 		return -EINVAL;
-	strncpy(devname, device + 5, sizeof(devname) - 1);
-	devname[sizeof(devname) - 1] = '\0';
 	strncpy(device_path, device, sizeof(device_path) - 1);
 
 	snprintf(unload_heads_path, sizeof(unload_heads_path) - 1,
-				"/sys/block/%s/device/unload_heads", devname);
+				"/sys/block/%s/device/unload_heads", device+5);
 	return 0;
 }