firewire: firewire-cdev.hL get rid of a docs warning

This warning:

	./include/uapi/linux/firewire-cdev.h:312: WARNING: Inline literal start-string without end-string.

is because %FOO doesn't work if there's a parenthesis at the
string (as a parenthesis may indicate a function). So, mark
the literal block using the alternate ``FOO`` syntax.
Acked-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/9b2501a41eba27ccdd4603cac2353c0efba7a90a.1586881715.git.mchehab+huawei@kernel.orgSigned-off-by: Jonathan Corbet <corbet@lwn.net>

include/uapi/linux/firewire-cdev.h

@@ -308,7 +308,7 @@ struct fw_cdev_event_iso_interrupt_mc {
 /**
  * struct fw_cdev_event_iso_resource - Iso resources were allocated or freed
  * @closure:	See &fw_cdev_event_common;
- *		set by %FW_CDEV_IOC_(DE)ALLOCATE_ISO_RESOURCE(_ONCE) ioctl
+ *		set by``FW_CDEV_IOC_(DE)ALLOCATE_ISO_RESOURCE(_ONCE)`` ioctl
  * @type:	%FW_CDEV_EVENT_ISO_RESOURCE_ALLOCATED or
  *		%FW_CDEV_EVENT_ISO_RESOURCE_DEALLOCATED
  * @handle:	Reference by which an allocated resource can be deallocated