x86-64: make pda's cpunumber and nodenumber unsigned

This generally allows better code to be generated, since the zero-
extension during 32-bit operations comes for free (needed when the
result is used as array index or similar), whereas sign extension must
be done explicitly and frequently requires a one byte larger
instruction due to the necessary rex64 prefix.

Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>