Update cochran depth precision: it's in 3-inch increments

The Cochran CSV depth exports are indeed in tenths of feet, but the
decimal is always 0, 3, 5 or 8.  Where the 3 and 8 are obviously 0.25
and 0.75 rounded up to one decimal place.

So Cochran does seem to be very much about imperial units, with depth
and cylinder pressure scaled by four (depth in quarter-foot increments,
pressume in 4-psi increments)

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

cochran.c

@@ -152,7 +152,7 @@ static void parse_cochran_header(const char *filename,
 
 /*
  * Cochran export files show that depths seem to be in
- * tenth of feet.
+ * quarter feet (rounded up to tenths).
  *
  * Temperature seems to be exported in Fahrenheit.
  *