b43: fix comment typo reqest -> request

Recent trivial fix corrected 'occured', but left 'reqest'.
codespell needs another dictionary entry.

cc: Lucas De Marchi <lucas.demarchi@profusion.mobi>
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>