s390/ap: remove unneeded semicolon

Remove a superfluous semicolon after function definition.

Signed-off-by: Chengyang Fan <cy.fan@huawei.com>
Message-Id: <20210125095839.1720265-1-cy.fan@huawei.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>