commit fce55481360d "ppc: A couple more dummy POWER8 Book4 regs"
squashed in to rapidly a set of POWER8 Book4 regs in the wrong
routine. This patch introduces the missing gen_spr_power8_book4()
routine to fix their location.
Signed-off-by: Cédric Le Goater <clg@fr.ibm.com> Signed-off-by: David Gibson <david@gibson.dropbear.id.au>