redhat/configs: Enable CONFIG_X86_KERNEL_IBT for Fedora and ARK

Kernel IBT is a nice kernel hardening feature with virtually no performance impact. Since commit 4fd5f70c ("x86/Kconfig: Enable kernel IBT by default"), its now enabled by default upstream. Enable it in Fedora and ARK as well.

Signed-off-by: Josh Poimboeuf jpoimboe@redhat.com