firewire: cdev: add ioctl for broadcast write requests

Write transactions to the broadcast node ID are a convenient way to
trigger functions of multiple nodes at once.  IIDC is a protocol which
can make use of this if multiple cameras with same command_regs_base are
connected at the same bus.

Based on
    Date: Wed, 10 Sep 2008 11:32:16 -0400
    From: Jay Fenlason <fenlason@redhat.com>
    Subject: [patch] SEND_BROADCAST_REQUEST
Changes:  ioctl_send_request() and ioctl_send_broadcast_request() now
share code.  Broadcast speed corrected to S100.  Check for proper tcode.

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
diff --git a/include/linux/firewire-cdev.h b/include/linux/firewire-cdev.h
index f819c10..340a785 100644
--- a/include/linux/firewire-cdev.h
+++ b/include/linux/firewire-cdev.h
@@ -230,6 +230,7 @@
 #define FW_CDEV_IOC_ALLOCATE_ISO_RESOURCE_ONCE   _IOW('#', 0x0f, struct fw_cdev_allocate_iso_resource)
 #define FW_CDEV_IOC_DEALLOCATE_ISO_RESOURCE_ONCE _IOW('#', 0x10, struct fw_cdev_allocate_iso_resource)
 #define FW_CDEV_IOC_GET_SPEED                    _IOR('#', 0x11, struct fw_cdev_get_speed)
+#define FW_CDEV_IOC_SEND_BROADCAST_REQUEST       _IOW('#', 0x12, struct fw_cdev_send_request)
 
 /* FW_CDEV_VERSION History
  *