ath9k: remove trailing semicolon in macro definition

The macro use will already have a semicolon.

Signed-off-by: Tom Rix <trix@redhat.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20201127175336.2752730-1-trix@redhat.com