config: switch to SLUB allocator

Since i have to compile my own modules with this kernel,
i can switch to a newer and faster memory allocator.

Some Benchmarks proved, that SLUB is (slightly) the fastest:

http://forum.xda-developers.com/showthread.php?t=1696284

Change-Id: I79c775d51a776f8b4ac6db67b0afad4fd281998a
Signed-off-by: Blechd0se <alex.christ@hotmail.de>
arm: atomic_t: Cast to volatile when accessing atomic variables

In preparation for removing volatile from the atomic_t definition, this
patch adds a volatile cast to all the arm atomic read functions.

Change-Id: Id77611dea7a2677c5dee96e8e838c35e89241ef8
Signed-off-by: Blechd0se <alex.christ@hotmail.de>