linux-yocto-efi-test: Update defconfig for v3.15

Using the default values.

Signed-off-by: Matt Fleming <matt.fleming@intel.com>
linux-yocto-efi-test: Enable CONFIG_EFI_BOOT_SERVICES_WARN

It's very useful to know if the firmware makes illegal accesses to the
EFI boot services regions. Enable CONFIG_EFI_BOOT_SERVICES_WARN which
prints a warning if such an access occurs.

Signed-off-by: Matt Fleming <matt.fleming@intel.com>