fix(B&W): Avoid having constants in SRAM (#2993)

fix constness to avoid having constants in data segment 
.... and thus free some precious RAM

radio/src/strhelpers.cpp

@@ -151,7 +151,7 @@ char *strcat_zchar(char *dest, const char *name, uint8_t size,
 #endif
 
 #if !defined(BOOT)
-char *getStringAtIndex(char *dest, const char **s, int idx)
+char *getStringAtIndex(char *dest, const char *const *s, int idx)
 {
   strcpy(dest, s[idx]);
   return dest;