docs: block: blk-mq.rst: correct drive -> driver

It is 'driver' to complete the request. Also remove a redundant space.
Signed-off-by: Yue Hu <huyue2@yulong.com>
Link: https://lore.kernel.org/r/20210520074225.1989-1-zbestahu@gmail.comSigned-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/block/blk-mq.rst

@@ -132,7 +132,7 @@ In order to indicate which request has been completed, every request is
 identified by an integer, ranging from 0 to the dispatch queue size. This tag
 is generated by the block layer and later reused by the device driver, removing
 the need to create a redundant identifier. When a request is completed in the
-drive, the tag is sent back to the block layer to notify it of the finalization.
+driver, the tag is sent back to the block layer to notify it of the finalization.
 This removes the need to do a linear search to find out which IO has been
 completed.