Remove wrongly repeated words in comments

Remove wrongly repeated words in comments

Clean up misrepetitions ('if if', 'the the' etc) found throughout the
comments. This has been done manually, after grepping
case-insensitively for duplicate if, is, the, then, do, for, an,
plus a few other typos corrected in fly-by

v2:
    * proper commit message and non-joke title;
    * replace two 'as is' followed by 'is' to 'as-is'.
v3:
    * 'a integer' => 'an integer' and similar (originally spotted by
      Jason Ekstrand, I fixed a few other similar ones while at it)

Signed-off-by: Giuseppe Bilotta <giuseppe.bilotta@gmail.com>
Reviewed-by: Chad Versace <chad.versace@intel.com>