w1: add 1-wire master driver for IP block found in SGI ASICs

Starting with SGI Origin machines nearly every new SGI ASIC contains
an 1-Wire master. They are used for attaching One-Wire prom devices,
which contain information about part numbers, revision numbers,
serial number etc. and MAC addresses for ethernet interfaces.
This patch adds a master driver to support this IP block.
It also adds an extra field dev_id to struct w1_bus_master, which
could be in used in slave drivers for creating unique device names.

Signed-off-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
Link: https://lore.kernel.org/r/20190831082623.15627-2-tbogendoerfer@suse.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

include/linux/w1.h

@@ -118,6 +118,9 @@ typedef void (*w1_slave_found_callback)(struct w1_master *, u64);
  * w1_master* is passed to the slave found callback.
  * u8 is search_type, W1_SEARCH or W1_ALARM_SEARCH
  *
+ * @dev_id: Optional device id string, which w1 slaves could use for
+ * creating names, which then give a connection to the w1 master
+ *
  * Note: read_bit and write_bit are very low level functions and should only
  * be used with hardware that doesn't really support 1-wire operations,
  * like a parallel/serial port.
@@ -150,6 +153,8 @@ struct w1_bus_master {
 
 	void		(*search)(void *, struct w1_master *,
 		u8, w1_slave_found_callback);
+
+	char		*dev_id;
 };
 
 /**