drivers: flash: stm32h7: do not unlock CR at the end of init

Do not unlock CR at the end of initialization.

The lock mechanism is to protect unwanted registers modifications due to
software bugs. There is no point in leaving the registers unlock once
the driver is initialized.

(cherry picked from commit 8aa4aa7)

Original-Signed-off-by: Dawid Niedzwiecki <[email protected]>
GitOrigin-RevId: 8aa4aa7
Cr-Build-Id: 8726453333733413585
Cr-Build-Url: https://cr-buildbucket.appspot.com/build/8726453333733413585
Copybot-Job-Name: zephyr-main-copybot-downstream
Change-Id: Id8f1c8c33fe694ee04f88d5e270876942270e742
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/zephyr/+/6150711
Tested-by: ChromeOS Prod (Robot) <[email protected]>
Bot-Commit: ChromeOS Prod (Robot) <[email protected]>
Commit-Queue: ChromeOS Prod (Robot) <[email protected]>

drivers/flash/flash_stm32h7x.c

@@ -767,7 +767,7 @@ static int stm32h7_flash_init(const struct device *dev)
 	}
 #endif
 
-	return flash_stm32h7_write_protection(dev, false);
+	return 0;
 }
 
 DEVICE_DT_INST_DEFINE(0, stm32h7_flash_init, NULL, &flash_data, NULL, POST_KERNEL,