[writeboost] Comments start from a capitalized letter

Other targets follows the rule that the comments start from
a capitalized letter. Writeboost should follow, too.

Signed-off-by: Akira Hayakawa <ruby.wktk@gmail.com>
[writeboost] purge wbdebug macro

This macro is not useful now.
Use tracing tool (e.g. systemtap) instead.

Signed-off-by: Akira Hayakawa <ruby.wktk@gmail.com>
[writeboost] Remove DMINFO in do_check_buffer_alignment()

This is only a debug code.
So, remove

Signed-off-by: Akira Hayakawa <ruby.wktk@gmail.com>
[writeboost] redesign error messages

Do like other targets do.

- dm-cache and dm-thin uses __func__ to identify the called routine
  So, using this is OK. <funcname>: ... is their way of formatting.
- Should be capitalized as comments.
- If the routine returned error is known its name then embed the name
  into the message. Other targets do so and actually helps grep.

Signed-off-by: Akira Hayakawa <ruby.wktk@gmail.com>
Merge pull request #12 from akiradeveloper/feature/cleanup

Feature/cleanup