x86: more users of PF_ constants in fault_32|64.c

Should be the last of the error_code tests that could use
the PF_ defines.  Makes X86_32|64 a little closer.

Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>