rtl8xxxu: Fix trailing semicolon

The trailing semicolon is an empty statement that does no operation.
Removing it since it doesn't do anything.

Signed-off-by: Luis de Bethencourt <luisbg@kernel.org>
Acked-by: Jes Sorensen <Jes.Sorensen@gmail.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>