openssd: fix styling

Fix styling according to linux kernel guidelines.

astyle -t8 -A9 --style=linux files
openssd: garbled comments...
openssd: remove printk
openssd: shift configuration flags

Forgot to shift the configuration flags as engine and the other flags
share data structure.
addded support for pack hints - writes related to files that have slow sequential read access
and are written and deleted as a unit. Example: video, mp3 etc.

- assuming we have multiple APs per pool, the last one in each AP is dedicated to packed writes.
- such an ap is associated to an inode number and all writes with a hint relating it an inode
that should be "pack"ed are written sequentially to this ap
- when the ap is full, we disassociate it from the ino, so it can service other inodes if necessary
  TODO: perhaps we can settle for the timeout (see next) and omit this code
- whenever a certain timeout passes (currently 10ms), the AP can be associated to an other inode.
  this helps avoid APs never getting new data, once a packed file is done writing.
openssd: move initialization of block from clean to when retrieved.

We do this to not sleep in the context of percpu_refcount release
function.
Merge branch 'openssd' of https://github.com/MatiasBjorling/linux_openssd into openssd
small fix of merge
openssd: percpu_refcount race-condition

We can't sleep in the context of percpu_refcount release function. We
therefore rearrange the code toward reset_block on when its being moved
to used list, instead of doing it when its added back to the free pool.
openssd: move diff_tv and openssd_phys_pack_addr to hint related source

It's better to keep hint related work outside the core path. This way
its easier to track bugs when they arrive, and we don't carry overhead
of hints that aren't enabled at some point.
openssd: do not cast directly

The code becomes unreadable when doing the casts inline.

It's okay to cast to the appropriate type and then set the structure
variable. By doing it that way, we explicit let the code reader know
what's happening.

In the end, its compiled to the same assembly code.
openssd: remove comment
openssd: after openssd_alloc_phys_pack_addr is moved to
dm-openssd-hint.c.

Its no longer need to define globally for the driver.
openssd: renaming block->parent_ap to block->ap

Just to keep it within naming convention and make it shorter. The pool
variable could also be parent_pool for clarity, but so far its less to
write.
openssd: group the logical variables together in block_reset
openssd: remove dminfo
openssd: refactor ap initialization
openssd: no need to print in the fast path.
openssd: code cleanup
openssd: alloc_phys_addr hook and move responsibility for hint