Don't include standard parser if hush is used

This saves about 1KB of code space on ARM with CONFIG_SYS_HUSH_PARSER
defined.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/common/main.c b/common/main.c
index 10ee12c..637da2b 100644
--- a/common/main.c
+++ b/common/main.c
@@ -1132,6 +1132,7 @@
 
 /****************************************************************************/
 
+#ifndef CONFIG_SYS_HUSH_PARSER
 static void process_macros (const char *input, char *output)
 {
 	char c, prev;
@@ -1382,6 +1383,7 @@
 
 	return rc ? rc : repeatable;
 }
+#endif
 
 /*
  * Run a command using the selected parser.