Fixes the following Coccinelle/coccicheck warning reported by
string_choices.cocci:

	opportunity for str_plural(days)
Signed-off-by: Thorsten Blum <thorsten.blum@toblux.com>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Link: https://lore.kernel.org/r/20240328140015.388654-3-thorsten.blum@toblux.comSigned-off-by: Daniel Thompson <daniel.thompson@linaro.org>