scripts/spelling.txt: add several more common spelling mistakes

Here are some of the more common spelling mistakes that I've found while
fixing up spelling mistakes in kernel error message text.  They probably
should be added to this list so we don't keep on seeing them appearing
again.

Link: http://lkml.kernel.org/r/20170421122534.5378-1-colin.king@canonical.com


Signed-off-by: Colin Ian King <colin.king@canonical.com>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Joe Perches <joe@perches.com>
Cc: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>