io/gzio: Properly init a table

ARRAY_SIZE() is the count of elements, but the element size is 4 bytes, so
this was only initing the first 1/4th of the table. Detected with valgrind.

This should only matter in error paths, and I've not been able to identify
any actual misbehaviour that results from reading in-bounds but uninited data.

Signed-off-by: Daniel Axtens <dja@axtens.net>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>

grub-core/io/gzio.c

@@ -524,7 +524,7 @@ huft_build (unsigned *b,	/* code lengths in bits (all assumed <= BMAX) */
     }
 
   /* Make a table of values in order of bit lengths */
-  grub_memset (v, N_MAX, ARRAY_SIZE (v));
+  grub_memset (v, N_MAX, sizeof (v));
   p = b;
   i = 0;
   do