fix a typo on comments in mm/percpu.c

'eqaul' should be 'equal'.
Signed-off-by: Namhyung Kim <namhyung@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

mm/percpu.c

@@ -31,7 +31,7 @@
  * as small as 4 bytes.  The allocator organizes chunks into lists
  * according to free size and tries to allocate from the fullest one.
  * Each chunk keeps the maximum contiguous area size hint which is
- * guaranteed to be eqaul to or larger than the maximum contiguous
+ * guaranteed to be equal to or larger than the maximum contiguous
  * area in the chunk.  This helps the allocator not to iterate the
  * chunk maps unnecessarily.
  *