x86: use cpu/common.c on 64 bit

Use cpu/common.c on both 64-bit and 32-bit and remove cpu/common_64.c.

We started out with this linecount:

  816  arch/x86/kernel/cpu/common_64.c
  805  arch/x86/kernel/cpu/common.c

and the resulting common.c is 1197 lines long, so there's already
424 lines of code eliminated in this phase of the unification.
Signed-off-by: NYinghai <yhlu.kernel@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

arch/x86/kernel/cpu/Makefile

@@ -3,10 +3,10 @@
 #
 
 obj-y			:= intel_cacheinfo.o addon_cpuid_features.o
-obj-y			+= proc.o capflags.o powerflags.o
+obj-y			+= proc.o capflags.o powerflags.o common.o
 
-obj-$(CONFIG_X86_32)	+= common.o bugs.o cmpxchg.o
-obj-$(CONFIG_X86_64)	+= common_64.o bugs_64.o
+obj-$(CONFIG_X86_32)	+= bugs.o cmpxchg.o
+obj-$(CONFIG_X86_64)	+= bugs_64.o
 
 obj-$(CONFIG_CPU_SUP_INTEL_32)		+= intel.o
 obj-$(CONFIG_CPU_SUP_INTEL_64)		+= intel_64.o