block: re-use existing 'reading' variable instead of checking direction again

Signed-off-by: majianpeng <majianpeng@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: umberto1978 <ur.tecnotop@gmail.com>
Removing i/o busy control from pegasusQ.
Thanks to Andreilux