Remove one unused variable

Saves 1 byte of SRAM

The variable is only assigned a value but is never used.

Firmware/Marlin.h

@@ -354,7 +354,6 @@ extern unsigned long start_pause_print;
 extern unsigned long t_fan_rising_edge;
 
 extern bool mesh_bed_leveling_flag;
-extern bool mesh_bed_run_from_menu;
 
 extern int8_t lcd_change_fil_state;
 // save/restore printing

Firmware/Marlin_main.cpp

@@ -208,7 +208,6 @@ static ShortTimer crashDetTimer;
 //unsigned long load_filament_time;
 
 bool mesh_bed_leveling_flag = false;
-bool mesh_bed_run_from_menu = false;
 
 #ifdef PRUSA_M28
 bool prusa_sd_card_upload = false;
@@ -3448,7 +3447,6 @@ static void gcode_G80()
     lcd_setstatuspgm(_T(WELCOME_MSG));
     custom_message_type = custom_message_type_old;
     custom_message_state = custom_message_state_old;
-    mesh_bed_run_from_menu = false;
     lcd_update(2);
 
     st_synchronize();

Firmware/ultralcd.cpp

@@ -4493,7 +4493,6 @@ static void lcd_language_menu()
 
 void lcd_mesh_bedleveling()
 {
-	mesh_bed_run_from_menu = true;
 	enquecommand_P(PSTR("G80"));
 	lcd_return_to_status();
 }