scripts/spelling.txt: add more spellings to spelling.txt

Some of the more common spelling mistakes and typos that I've found
while fixing up spelling mistakes in the kernel in the past few months.

Link: https://lkml.kernel.org/r/20210907072941.7033-1-colin.king@canonical.com


Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>