am335x_evm: Add command line editing

Many modern U-Boot ports enable command line editing and
a history buffer. The am335x_evm configuration is fairly
comprehensive as it is, so a few extra kb should not be
noticable, and it adds a very convenient feature.
Signed-off-by: NJustin Waters <justin.waters@timesys.com>

include/configs/am335x_evm.h

@@ -37,6 +37,9 @@
 #define CONFIG_OF_LIBFDT
 #define CONFIG_CMD_BOOTZ
 #define CONFIG_CMDLINE_TAG		/* enable passing of ATAGs */
+#define CONFIG_CMDLINE_EDITING
+#define CONFIG_STACKSIZE		(128 * 1024)
+#define CONFIG_AUTO_COMPLETE
 #define CONFIG_SETUP_MEMORY_TAGS
 #define CONFIG_INITRD_TAG