selftests/x86: Fix spelling mistake "preseve" -> "preserve"

Trivial fix to spelling mistakes in printf messages.

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Acked-by: Andy Lutomirski <luto@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kselftest@vger.kernel.org
Link: http://lkml.kernel.org/r/20160828105106.9763-1-colin.king@canonical.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>