mm/zsmalloc.c: fix duplicated words

Change "as as" to "as a".

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Link: http://lkml.kernel.org/r/20200801173822.14973-16-rdunlap@infradead.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/zsmalloc.c

@@ -79,7 +79,7 @@
 
 /*
  * Object location (<PFN>, <obj_idx>) is encoded as
- * as single (unsigned long) handle value.
+ * a single (unsigned long) handle value.
  *
  * Note that object index <obj_idx> starts from 0.
  *