drivers/staging/rtl8192u: fix indentation issue, remove extra tab

A statement is indented one level too deeply; clean this up by
removing a tab.
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Link: https://lore.kernel.org/r/20190723145022.11608-1-colin.king@canonical.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>