x86/build: Remove unnecessary preparation for purgatory

kexec-purgatory.c is properly generated when Kbuild descend into
the arch/x86/purgatory/.

Thus the 'archprepare' target is redundant.

Signed-off-by: Masahiro Yamada <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Michal Marek <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Sam Ravnborg <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Link: https://lore.kernel.org/lkml/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>

arch/x86/Makefile

@@ -258,11 +258,6 @@ archscripts: scripts_basic
 archheaders:
 	$(Q)$(MAKE) $(build)=arch/x86/entry/syscalls all
 
-archprepare:
-ifeq ($(CONFIG_KEXEC_FILE),y)
-	$(Q)$(MAKE) $(build)=arch/x86/purgatory arch/x86/purgatory/kexec-purgatory.c
-endif
-
 ###
 # Kernel objects