drivers/md: use time_before, time_before_eq, etc

The functions time_before, time_before_eq, time_after, and time_after_eq
are more robust for comparing jiffies against other values.

A simplified version of the semantic patch making this change is as follows:
(http://www.emn.fr/x-info/coccinelle/)

// <smpl>
@ change_compare_np @
expression E;
@@

(
- jiffies <= E
+ time_before_eq(jiffies,E)
|
- jiffies >= E
+ time_after_eq(jiffies,E)
|
- jiffies < E
+ time_before(jiffies,E)
|
- jiffies > E
+ time_after(jiffies,E)
)

@ include depends on change_compare_np @
@@

#include <linux/jiffies.h>

@ no_include depends on !include && change_compare_np @
@@

#include <linux/...>
+ #include <linux/jiffies.h>
// </smpl>

[[e-mail]: coding-style fixes]
Signed-off-by: Julia Lawall <[e-mail]>
Cc: Neil Brown <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

drivers/md/raid6algos.c

···
 			j0 = jiffies;
 			while ( (j1 = jiffies) == j0 )
 				cpu_relax();
-			while ( (jiffies-j1) < (1 << RAID6_TIME_JIFFIES_LG2) ) {
+			while (time_before(jiffies,
+					    j1 + (1<<RAID6_TIME_JIFFIES_LG2))) {
 				(*algo)->gen_syndrome(disks, PAGE_SIZE, dptrs);
 				perf++;
 			}