md/raid1,raid10: don't ignore IO flags

In the Linux kernel, the following vulnerability has been resolved: md/raid1,raid10: don't ignore IO flags If blk-wbt is enabled by default, it's found that raid write performance is quite bad because all IO are throttled by wbt of underlying disks, due to flag REQ_IDLE is ignored. And turns out this behaviour exist since blk-wbt is introduced. Other than REQ_IDLE, other flags should not be ignored as well, for example REQ_META can be set for filesystems, clearing it can cause priority reverse problems; And REQ_NOWAIT should not be cleared as well, because io will wait instead of failing directly in underlying disks. Fix those problems by keep IO flags from master bio. Fises: f51d46d0e7cb ("md: add support for REQ_NOWAIT")