verify: fix bytes_done accounting of experimental verify

verify: fix bytes_done accounting of experimental verify

The commit 55312f9f5572 ("Add ->bytes_done[] to struct thread_data")
moved bytes_done[] on stack to struct thread_data. However, this unified
two bytes_done[] in do_io() and do_verify() stacks into single
td->bytes_done[]. This caused wrong condition check in do_verify() in
experimental verify path since td->bytes_done[] holds values for do_io()
not for do_verify(). This caused unexpected loop break in do_verify()
and verify read skip when experimental_verify=1 option is specified.

To fix this, add bytes_verified to struct thread_data for do_verify() in
same manner as bytes_done[] for do_io(). Introduce a helper function
io_u_update_bytes_done() to factor out same code for bytes_done[] and
bytes_verified[].

Fixes: 55312f9f5572 ("Add ->bytes_done[] to struct thread_data")
Signed-off-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Signed-off-by: Vincent Fu <vincent.fu@samsung.com>