Revert "Fix derp introduced in f9caf4cfb63cac1495088d3efae6e7fede46f66c"

This reverts commit bf132125ea9b6adedb824994c10458be822bb2c5.
Revert "latest commits regarding extra free bytes and cma only for r4p0"

This reverts commit f9caf4cfb63cac1495088d3efae6e7fede46f66c.
Revert "mm: fix extra_free_kbytes tunable for CMA"

This reverts commit 89ed6ea918fad9c3abc45e0c56855648c180037e.
Revert "add extra free kbytes tunable"

This reverts commit 5b448a21a455a2ae9491b12155390b4dbbe0d3df.
Revert "Asynchronous I/O latency to a solid-state disk greatly increased"

This reverts commit 6c8a93e24499c50974f698fee126a120167f5d7a.