x86/shadow: More consistent printing for debug messages

x86/shadow: More consistent printing for debug messages

 * Use %pv or just d%d in preference to the multiple current ways of
   presenting the same information.
 * Use PRI_mfn instead of opencoding it.
 * Drop all explicit use of __func__ from SHADOW_{PRINTK,DEBUG}() calls.  The
   wrappers already include it.
 * Use hex rather than decimal for printing a pagefault error code.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Tim Deegan <tim@xen.org>