MIPS: MT: proc: Add support for printing VPE and TC ids

Add support for including VPE and TC ids in /proc/cpuinfo output as
appropriate when MT/SMTC is enabled.

Reviewed-by: James Hogan <james.hogan@imgtec.com>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Signed-off-by: John Crispin <blogic@openwrt.org>
Patchwork: http://patchwork.linux-mips.org/patch/6065/