powerpc: Add PVR & CPU name to hardware description

Add the PVR and CPU name to the hardware description, which is printed
at boot and in case of an oops.

eg: Hardware name: ... POWER8E (raw) 0x4b0201
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220930082709.55830-2-mpe@ellerman.id.au

arch/powerpc/kernel/prom.c

@@ -30,6 +30,7 @@
 #include <linux/libfdt.h>
 #include <linux/cpu.h>
 #include <linux/pgtable.h>
+#include <linux/seq_buf.h>
 
 #include <asm/rtas.h>
 #include <asm/page.h>
@@ -819,6 +820,9 @@ void __init early_init_devtree(void *params)
 
 	dt_cpu_ftrs_scan();
 
+	// We can now add the CPU name & PVR to the hardware description
+	seq_buf_printf(&ppc_hw_desc, "%s 0x%04lx ", cur_cpu_spec->cpu_name, mfspr(SPRN_PVR));
+
 	/* Retrieve CPU related informations from the flat tree
 	 * (altivec support, boot CPU ID, ...)
 	 */