firewire: core: fix overlooked update of subsystem ABI version

In kernel v6.5, several functions were added to the cdev layer. This
required updating the default version of subsystem ABI up to 6, but
this requirement was overlooked.

This commit updates the version accordingly.

Fixes: 6add87e ("firewire: cdev: add new version of ABI to notify time stamp at request/response subaction of transaction#")
Link: https://lore.kernel.org/r/20250920025148.163402-1-o-takashi@sakamocchi.jp
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>

Author: takaswie

drivers/firewire/core-cdev.c

@@ -41,7 +41,7 @@
 /*
  * ABI version history is documented in linux/firewire-cdev.h.
  */
-#define FW_CDEV_KERNEL_VERSION			5
+#define FW_CDEV_KERNEL_VERSION			6
 #define FW_CDEV_VERSION_EVENT_REQUEST2		4
 #define FW_CDEV_VERSION_ALLOCATE_REGION_END	4
 #define FW_CDEV_VERSION_AUTO_FLUSH_ISO_OVERFLOW	5