Correct trivial typo in log2.h.

Single typo correction in include/linux/log2.h.
Signed-off-by: Robert P. J. Day <rpjday@mindspring.com>
Signed-Off-By: David Howells <dhowells@redhat.com>
Signed-off-by: Adrian Bunk <bunk@stusta.de>

include/linux/log2.h

@@ -152,7 +152,7 @@ unsigned long __roundup_pow_of_two(unsigned long n)
  * roundup_pow_of_two - round the given value up to nearest power of two
  * @n - parameter
  *
- * round the given balue up to the nearest power of two
+ * round the given value up to the nearest power of two
  * - the result is undefined when n == 0
  * - this can be used to initialise global variables from constant data
  */