stm32: return early upon block write failure

only if we do not have enough ram do we continue.

Signed-off-by: Øyvind Harboe <oyvind.harboe@zylin.com>

src/flash/nor/stm32x.c

@@ -668,6 +668,9 @@ static int stm32x_write(struct flash_bank *bank, uint8_t *buffer,
 		}
 	}
 
+	if ((retval != ERROR_OK) && (retval != ERROR_TARGET_RESOURCE_NOT_AVAILABLE))
+		return retval;
+
 	while (words_remaining > 0)
 	{
 		uint16_t value;