staging: vchiq_core: Simplify vchiq_bulk_transfer()

staging: vchiq_core: Simplify vchiq_bulk_transfer()

Factor out core logic for preparing bulk data transfer(mutex locking,
waits on vchiq_bulk_queue wait-queue, initialising the bulk transfer)
out of the vchiq_bulk_transfer(). This simplifies the existing
vchiq_bulk_transfer() and makes it more readable since all the core
logic is handled in vchiq_bulk_xfer_queue_msg_interruptible(). It
will also help us to refactor vchiq_bulk_transfer() easily for different
vchiq bulk transfer modes.

No functional changes intended in this patch.

Signed-off-by: Umang Jain <umang.jain@ideasonboard.com>
Tested-by: Stefan Wahren <wahrenst@gmx.net>
Link: https://lore.kernel.org/r/20240910051007.297227-3-umang.jain@ideasonboard.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>