x86_64: Enable PEP target on x86_64 for efi support in binutils

To allow create of binaries for use with EFI we need to enable the
x86_64-pep target in binutils.

Signed-off-by: Kumar Gala <kumar.gala@linaro.org>

configs/x86_64-zephyr-elf.config

@@ -10,6 +10,7 @@ CT_MULTILIB=y
 CT_ARCH_64=y
 CT_TARGET_VENDOR="zephyr"
 CT_BINUTILS_V_2_35=y
+CT_BINUTILS_EXTRA_CONFIG_ARRAY="--enable-targets=x86_64-pep"
 CT_NEWLIB_SRC_DEVEL=y
 CT_NEWLIB_DEVEL_URL="https://github.com/zephyrproject-rtos/newlib-cygwin.git"
 CT_NEWLIB_DEVEL_REVISION="b1fe4401fdbd0860e0b91227219b15d2e0142b78"