net/ieee802154: fix repeated words in comments

Delete the redundant word 'was'.

Signed-off-by: Jilin Yuan <yuanjilin@cdjrlc.com>
Link: https://lore.kernel.org/r/20220708151538.51483-1-yuanjilin@cdjrlc.com


Signed-off-by: Stefan Schmidt <stefan@datenfreihafen.org>