md/raid1: properly indicate failure when ending a failed write request

commit 2417b9869b81882ab90fd5ed1081a1cb2d4db1dd upstream.

This patch addresses a data corruption bug in raid1 arrays using bitmaps.
Without this fix, the bitmap bits for the failed I/O end up being cleared.

Since we are in the failure leg of raid1_end_write_request, the request
either needs to be retried (R1BIO_WriteError) or failed (R1BIO_Degraded).

Fixes: eeba6809d8d5 ("md/raid1: end bio when the device faulty")
Cc: stable@vger.kernel.org # v5.2+
Signed-off-by: Paul Clements <paul.clements@us.sios.com>
Signed-off-by: Song Liu <song@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>