powerpc/64s: Remove WORT SPR from POWER9/10 (take 2)

This removes a missed remnant of the WORT SPR.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211123095231.1036501-2-npiggin@gmail.com