x86/CPU: Fix unused variable warning when !CONFIG_IA32_EMULATION

Get rid of local @cpu variable which is unused in the
!CONFIG_IA32_EMULATION case.

Signed-off-by: zhong jiang <zhongjiang@huawei.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: David Woodhouse <dwmw@amazon.co.uk>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Pavel Tatashin <pasha.tatashin@oracle.com>
Cc: x86-ml <x86@kernel.org>
Link: http://lkml.kernel.org/r/1536806985-24197-1-git-send-email-zhongjiang@huawei.com


[ Clean up commit message. ]
Signed-off-by: Borislav Petkov <bp@suse.de>