common: Tidy up how malloc() is inited

The call to malloc() is a bit strange. The naming of the arguments
suggests that an address is passed, but in fact it is a pointer, at
least in the board_init_r() function and SPL equivalent.

Update it to work as described. Add a function comment as well.

Note that this does adjustment does not extend into the malloc()
implementation itself, apart from changing mem_malloc_init(), since
there are lots of casts and pointers and integers are used
interchangeably.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>

common/board_r.c

@@ -204,8 +204,7 @@ static int initr_malloc(void)
 	 */
 	start = gd->relocaddr - TOTAL_MALLOC_LEN;
 	gd_set_malloc_start(start);
-	mem_malloc_init((ulong)map_sysmem(start, TOTAL_MALLOC_LEN),
-			TOTAL_MALLOC_LEN);
+	mem_malloc_init(start, TOTAL_MALLOC_LEN);
 	return 0;
 }