Revert "blk-mq: introduce blk_mq_map_hw_queues"

This reverts commit fe2bdefe which is
commit 1452e9b4 upstream.

It breaks the Android kernel abi and can be brought back in the future
in an abi-safe way if it is really needed.

Bug: 161946584
Change-Id: If3c20ff7c3c9cf9ba53bb387eb59f3d564d12666
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>