powerpc: Remove powerpc specific cmd_line

There is no need for yet another copy of the command line, just
use boot_command_line like everyone else.

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

drivers/tty/hvc/hvc_vio.c

@@ -452,7 +452,7 @@ void __init hvc_vio_init_early(void)
 		return;
 #endif
 	/* Check whether the user has requested a different console. */
-	if (!strstr(cmd_line, "console="))
+	if (!strstr(boot_command_line, "console="))
 		add_preferred_console("hvc", 0, NULL);
 	hvc_instantiate(0, 0, ops);
 }