powerpc: Remove unused prototype for of_show_percpuinfo

commit 6d7f58b0 ("[PATCH] powerpc: Some minor cleanups to setup_32.c")
removed of_show_percpuinfo but didn't remove the prototype.

Remove it.

Fixes: 6d7f58b0 ("[PATCH] powerpc: Some minor cleanups to setup_32.c")
Signed-off-by: Daniel Axtens <dja@axtens.net>
Reviewed-by: Andrew Donnellan <ajd@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210903063246.70691-1-dja@axtens.net

arch/powerpc/platforms/powermac/pmac.h

@@ -27,7 +27,6 @@ extern void pmac_nvram_update(void);
 extern unsigned char pmac_nvram_read_byte(int addr);
 extern void pmac_nvram_write_byte(int addr, unsigned char val);
 extern void pmac_pcibios_after_init(void);
-extern int of_show_percpuinfo(struct seq_file *m, int i);
 
 extern void pmac_setup_pci_dma(void);
 extern void pmac_check_ht_link(void);