powerpc/prom: Drop support for old FDT versions

In commit e6a6928c3ea1 ("of/fdt: Convert FDT functions to use
libfdt") (Apr 2014), the generic flat device tree code dropped support
for flat device tree's older than version 0x10 (16).

We still have code in our CPU scanning to cope with flat device tree
versions earlier than 2, which can now never trigger, so drop it.

Signed-off-by: Michael Ellerman <[e-mail]>

arch/powerpc/kernel/prom.c

···
 	 * NOTE: This must match the parsing done in smp_setup_cpu_maps.
 	 */
 	for (i = 0; i < nthreads; i++) {
-		/*
-		 * version 2 of the kexec param format adds the phys cpuid of
-		 * booted proc.
-		 */
-		if (fdt_version(initial_boot_params) >= 2) {
-			if (be32_to_cpu(intserv[i]) ==
-			    fdt_boot_cpuid_phys(initial_boot_params)) {
-				found = boot_cpu_count;
-				found_thread = i;
-			}
-		} else {
-			/*
-			 * Check if it's the boot-cpu, set it's hw index now,
-			 * unfortunately this format did not support booting
-			 * off secondary threads.
-			 */
-			if (of_get_flat_dt_prop(node,
-					"linux,boot-cpu", NULL) != NULL)
-				found = boot_cpu_count;
+		if (be32_to_cpu(intserv[i]) ==
+			fdt_boot_cpuid_phys(initial_boot_params)) {
+			found = boot_cpu_count;
+			found_thread = i;
 		}
 #ifdef CONFIG_SMP
 		/* logical cpu id is always 0 on UP kernels */