drivers/watchdog/: Spelling fixes

Signed-off-by: Joe Perches <[e-mail]>
Signed-off-by: Adrian Bunk <[e-mail]>

drivers/watchdog/shwdt.c

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  * overflow periods respectively.
  *
  * Also, since we can't really expect userspace to be responsive enough
- * before the overflow happens, we maintain two seperate timers .. One in
+ * before the overflow happens, we maintain two separate timers .. One in
  * the kernel for clearing out WOVF every 2ms or so (again, this depends on
  * HZ == 1000), and another for monitoring userspace writes to the WDT device.
  *