ctx: Rename fonts to match font number

Renames font constants so they match the indexing used by
ctx_get_font_name.

components/ctx/ctx_config.h

@@ -95,10 +95,10 @@
 #define CTX_FONT_3 CTX_STATIC_FONT(Arimo_BoldItalic)
 
 #include "Tinos-Regular.h"
-#define CTX_FONT_13 CTX_STATIC_FONT(Tinos_Regular)
+#define CTX_FONT_4 CTX_STATIC_FONT(Tinos_Regular)
 
 #include "Cousine-Regular.h"
 #include "Cousine-Bold.h"
-#define CTX_FONT_21 CTX_STATIC_FONT(Cousine_Regular)
-#define CTX_FONT_22 CTX_STATIC_FONT(Cousine_Bold)
+#define CTX_FONT_5 CTX_STATIC_FONT(Cousine_Regular)
+#define CTX_FONT_6 CTX_STATIC_FONT(Cousine_Bold)