x86/platform: Add kvmconfig to the phony targets

... so as not to disable it with a file of the same name in the
toplevel build directory.
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: http://lkml.kernel.org/r/1371801891-23618-1-git-send-email-bp@alien8.deSigned-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/Makefile

@@ -220,6 +220,7 @@ archclean:
 	$(Q)$(MAKE) $(clean)=$(boot)
 	$(Q)$(MAKE) $(clean)=arch/x86/tools
 
+PHONY += kvmconfig
 kvmconfig:
 	$(if $(wildcard $(objtree)/.config),, $(error You need an existing .config for this target))
 	$(Q)$(CONFIG_SHELL) $(srctree)/scripts/kconfig/merge_config.sh -m -O $(objtree) $(objtree)/.config arch/x86/configs/kvm_guest.config