lib/utils: Remove unused PYEXEC_SWITCH_MODE from pyexec.h.

It was made obsolete by commit c98c128fe8.

Signed-off-by: Damien George <damien@micropython.org>

lib/utils/pyexec.h

@@ -41,7 +41,6 @@ extern pyexec_mode_kind_t pyexec_mode_kind;
 extern int pyexec_system_exit;
 
 #define PYEXEC_FORCED_EXIT (0x100)
-#define PYEXEC_SWITCH_MODE (0x200)
 
 int pyexec_raw_repl(void);
 int pyexec_friendly_repl(void);