sandbox: Increase memory size to 32MB

The current 4MB size is a little small for some tests, so increase it.

Reviewed-by: Hung-ying Tyan <tyanh@chromium.org>
Signed-off-by: Simon Glass <sjg@chromium.org>

include/configs/sandbox.h

@@ -66,7 +66,7 @@
 /*
  * Size of malloc() pool, although we don't actually use this yet.
  */
-#define CONFIG_SYS_MALLOC_LEN		(4 << 20)	/* 4MB  */
+#define CONFIG_SYS_MALLOC_LEN		(32 << 20)	/* 32MB  */
 
 #define CONFIG_SYS_HUSH_PARSER
 #define CONFIG_SYS_LONGHELP			/* #undef to save memory */