staging: vc04_services: Improve readability of kthread names

This patch tries to make the kernel thread names of vchiq a little
bit more self explaining and look closer to the existing ones:

slot handler: VCHIQ-%d -> vchiq-slot/%d
recycle thread: VCHIQr-%d -> vchiq-recy/%d
sync thread: VCHIQs-%d -> vhciq-sync/%d
keep-alive thread: VCHIQka-%d -> vchiq-keep/%d

Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>