x86/platform/uv: Remove dead !CONFIG_KEXEC_CORE code

The !CONFIG_KEXEC_CORE code in arch/x86/platform/uv/uv_nmi.c was unused, untested
and didn't even build for 7 years. Since we fixed this by requiring X86_UV to
depend on CONFIG_KEXEC_CORE, remove the (now) dead code.

Also move the uv_nmi_kexec_failed definition back up to where the other file-scope
global variables are defined.

Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Mike Travis <travis@sgi.com>
Cc: linux-kernel@vger.kernel.org