powerpc/powernv/idle: Replace CPU feature check with PVR check

The POWER9 idle driver contains implementation-specific details that
means it is not suitable to run on any processor that implements ISA
v3.0 (e.g., POWER10), so only init the driver when running on a
POWER9.

Signed-off-by: Pratik Rajesh Sampat <psampat@linux.ibm.com>
[mpe: Use updated change log from Nick]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200721153708.89057-2-psampat@linux.ibm.com

arch/powerpc/platforms/powernv/idle.c

@@ -1223,7 +1223,7 @@ static void __init pnv_probe_idle_states(void)
 		return;
 	}
 
-	if (cpu_has_feature(CPU_FTR_ARCH_300))
+	if (pvr_version_is(PVR_POWER9))
 		pnv_power9_idle_init();
 
 	for (i = 0; i < nr_pnv_idle_states; i++)