fix(st-ddr): remove TODO in STM32MP2 driver

Remove useless ddr_get_io_calibration_val service.
Other items are deleted as they're useless on STM32MP2 series.

Signed-off-by: Nicolas Le Bayon <nicolas.le.bayon@foss.st.com>
Change-Id: I30bb18f156ff6dc06147987654363472a1e0182d
diff --git a/include/drivers/st/stm32mp2_ddr_helpers.h b/include/drivers/st/stm32mp2_ddr_helpers.h
index 9329fff..d9bf7ae 100644
--- a/include/drivers/st/stm32mp2_ddr_helpers.h
+++ b/include/drivers/st/stm32mp2_ddr_helpers.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2024, STMicroelectronics - All Rights Reserved
+ * Copyright (c) 2024-2025, STMicroelectronics - All Rights Reserved
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -22,7 +22,6 @@
 void ddr_activate_controller(struct stm32mp_ddrctl *ctl, bool sr_entry);
 void ddr_wait_lp3_mode(bool state);
 int ddr_sr_exit_loop(void);
-uint32_t ddr_get_io_calibration_val(void);
 int ddr_sr_entry(bool standby);
 int ddr_sr_exit(void);
 enum stm32mp2_ddr_sr_mode ddr_read_sr_mode(void);