Documentation: ieee802154: fix grammar

Fix grammar where it improves readability.

Signed-off-by: Leo Stone <leocstone@gmail.com>
Reviewed-by: Miquel Raynal <miquel.raynal@bootlin.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Reviewed-by: Bagas Sanjaya <bagasdotme@gmail.com>
Link: https://lore.kernel.org/20241023041203.35313-1-leocstone@gmail.com


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