staging: vchiq: Rename vchiq_completion_data 'bulk_userdata'

staging: vchiq: Rename vchiq_completion_data 'bulk_userdata'

In a previous commit, struct vchiq_bulk 'userdata' got renamed to
'cb_data' since it is the data pointer passed in
VCHIQ_BULK_CALLBACK_MODE's callback. Since struct vchiq_completion_data*
structs also has 'bulk_userdata' for completion records, rename
'bulk_userdata' member to 'cb_data' for these structs as well.

This brings consistency and clarity for the struct members. No
functional change in this patch.

Signed-off-by: Umang Jain <umang.jain@ideasonboard.com>
Link: https://lore.kernel.org/r/20241023110406.885199-5-umang.jain@ideasonboard.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>