MIPS: Detect MIPSr6 Virtual Processor support

MIPS: Detect MIPSr6 Virtual Processor support

MIPSr6 introduces support for "Virtual Processors", which are
conceptually similar to VPEs from the now-deprecated MT ASE. Detect
whether the system supports VPs using the VP bit in Config5, adding
cpu_has_vp for use by later patches.

Signed-off-by: Paul Burton <[email protected]>
Cc: [email protected]
Cc: Maciej W. Rozycki <[email protected]>
Cc: Joshua Kinard <[email protected]>
Cc: Steven J. Hill <[email protected]>
Cc: Leonid Yegoshin <[email protected]>
Cc: James Hogan <[email protected]>
Cc: [email protected]
Patchwork: https://patchwork.linux-mips.org/patch/12327/
Signed-off-by: Ralf Baechle <[email protected]>