x86/microcode: Correct Kconfig dependencies

I have a randconfig here which has enabled only

  CONFIG_MICROCODE=y
  CONFIG_MICROCODE_OLD_INTERFACE=y

with both

  # CONFIG_MICROCODE_INTEL is not set
  # CONFIG_MICROCODE_AMD is not set

off. Which makes building the microcode functionality a little
pointless. Don't do that in such cases then.
Signed-off-by: NBorislav Petkov <bp@suse.de>
Link: http://lkml.kernel.org/r/1381682189-14470-1-git-send-email-bp@alien8.deSigned-off-by: NIngo Molnar <mingo@kernel.org>

arch/x86/Kconfig

@@ -1033,6 +1033,7 @@ config X86_REBOOTFIXUPS
 
 config MICROCODE
 	tristate "CPU microcode loading support"
+	depends on CPU_SUP_AMD || CPU_SUP_INTEL
 	select FW_LOADER
 	---help---