Command usage cleanup

Remove command name from all command "usage" fields and update
common/command.c to display "name - usage" instead of
just "usage". Also remove newlines from command usage fields.

Signed-off-by: Peter Tyser <ptyser@xes-inc.com>
diff --git a/common/cmd_strings.c b/common/cmd_strings.c
index 6f0cbca..4517ba2 100644
--- a/common/cmd_strings.c
+++ b/common/cmd_strings.c
@@ -41,6 +41,6 @@
 }
 
 U_BOOT_CMD(strings, 3, 1, do_strings,
-	"strings - display strings\n",
+	"display strings",
 	"<addr> [byte count]\n"
 	"    - display strings at <addr> for at least [byte count] or first double NUL\n");