stm32/sdram: Fix to use new mpu_config_start/mpu_config_end signature.

Author: pi-anl

ports/stm32/sdram.c

@@ -248,10 +248,10 @@ static void sdram_init_seq(SDRAM_HandleTypeDef
        Initially disable all access for the entire SDRAM memory space,
        then enable access/caching for the size used
     */
-    mpu_config_start();
+    uint32_t irq_state = mpu_config_start();
     mpu_config_region(MPU_REGION_SDRAM1, SDRAM_START_ADDRESS, MPU_CONFIG_DISABLE(0x00, MPU_REGION_SIZE_512MB));
     mpu_config_region(MPU_REGION_SDRAM2, SDRAM_START_ADDRESS, MPU_CONFIG_SDRAM(SDRAM_MPU_REGION_SIZE));
-    mpu_config_end();
+    mpu_config_end(irq_state);
     #endif
 }