[POWERPC] Setup RTAS values earlier, to enable rtas_call() earlier

Althought RTAS is instantiated when we enter the kernel, we can't actually
call into it until we know its entry point address. Currently we grab that
in rtas_initialize(), however that's quite late in the boot sequence.

To enable rtas_call() earlier, we can grab the RTAS entry etc. values while
we're scanning the flattened device tree. There's existing code to retrieve
the values from /chosen, however we don't store them there anymore, so remove
that code.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/include/asm-powerpc/rtas.h b/include/asm-powerpc/rtas.h
index 02e213e..a33c6ac 100644
--- a/include/asm-powerpc/rtas.h
+++ b/include/asm-powerpc/rtas.h
@@ -181,6 +181,9 @@
 extern unsigned int rtas_busy_delay_time(int status);
 extern unsigned int rtas_busy_delay(int status);
 
+extern int early_init_dt_scan_rtas(unsigned long node,
+		const char *uname, int depth, void *data);
+
 extern void pSeries_log_error(char *buf, unsigned int err_type, int fatal);
 
 /* Error types logged.  */