flash/nor/stm32f1x: unify flash error reporting

stm32x_wait_status_busy() has two side effects in case of flash programming error:
- reports error
- clears error bit in status register

Use stm32x_wait_status_busy() to report also flash error during target
algo flash write.

While on it use more descriptive error codes in stm32x_wait_status_busy().

Change-Id: I6e1cffc2aa5411b918a23ed62d5194910888a9d1
Signed-off-by: Tomas Vanek <vanekt@fbl.cz>
Reviewed-on: https://review.openocd.org/c/openocd/+/6709
Tested-by: jenkins
Reviewed-by: Tarek BOCHKATI <tarek.bouchkati@gmail.com>