chore(cleanup): remove now obsolete screen_putstring prototyp

Author: nick-less

lib/screen.h

@@ -13,7 +13,6 @@ extern uint16_t _screen_getsize(void);
 extern void _screen_setcursor(uint16_t c);
 extern uint16_t _screen_getcursor(void);
 extern void screen_putchar(char c);
-extern void screen_putstring(const char* s);
 extern void _screen_putstring(uint16_t s);
 extern uint16_t screen_getchar(uint16_t timeout_cs);
 extern uint8_t screen_waitchar(void);