x86, doc, kconfig: Fix dud URL for Microcode data

The actual data lives in the Intel download center, and that ought to also
be a reliable way to continue to find it. Unfortunately the actual URL
needed for doing it directly is about a foot long so give instructions.
Signed-off-by: Alan Cox <alan@linux.intel.com>
Link: http://lkml.kernel.org/r/20140120180056.7173.62222.stgit@alan.etchedpixels.co.ukSigned-off-by: H. Peter Anvin <hpa@zytor.com>

arch/x86/Kconfig

@@ -1064,9 +1064,9 @@ config MICROCODE_INTEL
 	  This options enables microcode patch loading support for Intel
 	  processors.
 
-	  For latest news and information on obtaining all the required
-	  Intel ingredients for this driver, check:
-	  <http://www.urbanmyth.org/microcode/>.
+	  For the current Intel microcode data package go to
+	  <https://downloadcenter.intel.com> and search for
+	  'Linux Processor Microcode Data File'.
 
 config MICROCODE_AMD
 	bool "AMD microcode loading support"