x86/lguest: Use __pa_symbol instead of __pa on C visible symbols

The function lguest_write_cr3 is using __pa to convert swapper_pg_dir and
initial_page_table from virtual addresses to physical.  The correct function
to use for these values is __pa_symbol since they are C visible symbols.

Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Link: http://lkml.kernel.org/r/20121116215748.8521.83556.stgit@ahduyck-cp1.jf.intel.comSigned-off-by: H. Peter Anvin <hpa@linux.intel.com>

arch/x86/lguest/boot.c

@@ -552,7 +552,8 @@ static void lguest_write_cr3(unsigned long cr3)
 	current_cr3 = cr3;
 
 	/* These two page tables are simple, linear, and used during boot */
-	if (cr3 != __pa(swapper_pg_dir) && cr3 != __pa(initial_page_table))
+	if (cr3 != __pa_symbol(swapper_pg_dir) &&
+	    cr3 != __pa_symbol(initial_page_table))
 		cr3_changed = true;
 }