x86-64: add CONFIG_PHYSICAL_ALIGN for consistency with i386

Add CONFIG_PHYSICAL_ALIGN (currently as a hardcoded constant) to provide
consistency with i386.  This value is manifest in the bzImage header.
Signed-off-by: NH. Peter Anvin <hpa@zytor.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

arch/x86_64/Kconfig

@@ -427,6 +427,10 @@ config NR_CPUS
 	  This is purely to save memory - each supported CPU requires
 	  memory in the static kernel configuration.
 
+config PHYSICAL_ALIGN
+	hex
+	default "0x200000"
+
 config HOTPLUG_CPU
 	bool "Support for suspend on SMP and hot-pluggable CPUs (EXPERIMENTAL)"
 	depends on SMP && HOTPLUG && EXPERIMENTAL