checkpatch: fix false positive on __initconst

checkpatch falsely complained about '__initconst' because it thought the
'const' needed a space before.  Fix this by changing the list of
attributes:

- add '__initconst'
- force plain 'init' to contain a word-boundary at the end

Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
Cc: Andy Whitcroft <apw@shadowen.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>