block: cfq: tweak all CFQ tunables. Researched by my mates malaroth, osm0sis, joaquinf, The Gingerbread Man, pkgnex, Khrushy, shreddintyres. Please if you copy this values make sure you cherry-pick it properly and leave these guys in the commit message, they researched this for a long time.

Signed-off-by: Francisco Franco <franciscofranco.1990@gmail.com>