x86: ivybridge: Do not require HAVE_INTEL_ME

Do not set HAVE_INTEL_ME by default as for some cases Intel ME
firmware even does not reside on the same SPI flash as U-Boot.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Simon Glass <sjg@chromium.org>
Tested-by: Simon Glass <sjg@chromium.org>