flash/nor: Do not update 'is_erased'

Remove useless setting of the 'is_erased' flag after a flash
modification. Also, remove code that erroneously depends on
this flag.

Keep the flag for now since it is still used by the
erase_check() functionality.

See commit 07da3b3913

Change-Id: Ia046905bc9e0cb2572145f19251c3e10c4e2d553
Signed-off-by: Marc Schink <dev@zapb.de>
Reviewed-on: http://openocd.zylin.com/6279
Tested-by: jenkins
Reviewed-by: Tarek BOCHKATI <tarek.bouchkati@gmail.com>
Reviewed-by: Tomas Vanek <vanekt@fbl.cz>
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>

src/flash/nor/stmqspi.c

@@ -588,18 +588,13 @@ COMMAND_HANDLER(stmqspi_handle_mass_erase_command)
 	retval = wait_till_ready(bank, SPI_MASS_ERASE_TIMEOUT);
 
 	duration_measure(&bench);
-	if (retval == ERROR_OK) {
-		/* set all sectors as erased */
-		for (sector = 0; sector < bank->num_sectors; sector++)
-			bank->sectors[sector].is_erased = 1;
-
+	if (retval == ERROR_OK)
 		command_print(CMD, "stmqspi mass erase completed in %fs (%0.3f KiB/s)",
 			duration_elapsed(&bench),
 			duration_kbps(&bench, bank->size));
-	} else {
+	else
 		command_print(CMD, "stmqspi mass erase not completed even after %fs",
 			duration_elapsed(&bench));
-	}
 
 err:
 	/* Switch to memory mapped mode before return to prompt */