virt: vbox: Fix some comments which talk about the "session spinlock"

The session lock is a mutex, not a spinlock, fix the comments to match.

Acked-by: Arnd Bergmann <[e-mail]>
Signed-off-by: Hans de Goede <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/virt/vboxguest/vboxguest_core.c

···
  * Changes the event filter mask for the given session.
  *
  * This is called in response to VBG_IOCTL_CHANGE_FILTER_MASK as well as to
- * do session cleanup. Takes the session spinlock.
+ * do session cleanup. Takes the session mutex.
  *
  * Return: 0 or negative errno value.
  * @gdev:			The Guest extension device.
···
 }
 
 /**
- * Sets the guest capabilities for a session. Takes the session spinlock.
+ * Sets the guest capabilities for a session. Takes the session mutex.
  * Return: 0 or negative errno value.
  * @gdev:			The Guest extension device.
  * @session:			The session.