x86: remove pda.h

Impact: cleanup

Signed-off-by: Brian Gerst <brgerst@gmail.com>

arch/x86/kernel/process_64.c

@@ -47,7 +47,6 @@
 #include <asm/processor.h>
 #include <asm/i387.h>
 #include <asm/mmu_context.h>
-#include <asm/pda.h>
 #include <asm/prctl.h>
 #include <asm/desc.h>
 #include <asm/proto.h>