uprobes/core: Clean up, refactor and improve the code

uprobes/core: Clean up, refactor and improve the code

Make the uprobes code readable to me:

 - improve the Kconfig text so that a mere mortal gets some idea
   what CONFIG_UPROBES=y is really about

 - do trivial renames to standardize around the uprobes_*() namespace

 - clean up and simplify various code flow details

 - separate basic blocks of functionality

 - line break artifact and white space related removal

 - use standard local varible definition blocks

 - use vertical spacing to make things more readable

 - remove unnecessary volatile

 - restructure comment blocks to make them more uniform and
   more readable in general

Cc: Srikar Dronamraju <[email protected]>
Cc: Jim Keniston <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Oleg Nesterov <[email protected]>
Cc: Masami Hiramatsu <[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
Cc: Anton Arapov <[email protected]>
Cc: Ananth N Mavinakayanahalli <[email protected]>
Link: http://lkml.kernel.org/n/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>