of/flattree: Eliminate need to provide early_init_dt_scan_chosen_arch

This patch refactors the early init parsing of the chosen node so that
architectures aren't forced to provide an empty implementation of
early_init_dt_scan_chosen_arch.  Instead, if an architecture wants to
do something different, it can either use a wrapper function around
early_init_dt_scan_chosen(), or it can replace it altogether.

This patch was written in preparation to adding device tree support to
both x86 ad MIPS.

Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Tested-by: David Daney <ddaney@caviumnetworks.com>

drivers/of/fdt.c

@@ -533,8 +533,6 @@ int __init early_init_dt_scan_chosen(unsigned long node, const char *uname,
 		strlcpy(cmd_line, CONFIG_CMDLINE, COMMAND_LINE_SIZE);
 #endif /* CONFIG_CMDLINE */
 
-	early_init_dt_scan_chosen_arch(node);
-
 	pr_debug("Command line is: %s\n", cmd_line);
 
 	/* break now */