m68k: amiga: Use str_plural() to fix Coccinelle warning

Fixes the following Coccinelle/coccicheck warning reported by
string_choices.cocci:

	opportunity for str_plural(zorro_num_autocon)

Signed-off-by: Thorsten Blum <thorsten.blum@toblux.com>
Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>
Link: https://lore.kernel.org/r/20240412215704.204403-4-thorsten.blum@toblux.com
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>

Author: toblux

arch/m68k/amiga/config.c

@@ -836,7 +836,7 @@ static void amiga_get_hardware_list(struct seq_file *m)
 		seq_printf(m, "\tZorro II%s AutoConfig: %d Expansion "
 				"Device%s\n",
 				AMIGAHW_PRESENT(ZORRO3) ? "I" : "",
-				zorro_num_autocon, zorro_num_autocon == 1 ? "" : "s");
+				zorro_num_autocon, str_plural(zorro_num_autocon));
 #endif /* CONFIG_ZORRO */
 
 #undef AMIGAHW_ANNOUNCE