accel/ivpu: Fix old dma_buf api usage

Update according to new dma-buf locking scheme.

Remove redundant WARN_ON()'s, dma_buf functions internally
have the same warnings already.

Signed-off-by: Stanislaw Gruszka <stanislaw.gruszka@linux.intel.com>
Reviewed-by: Jeffrey Hugo <quic_jhugo@quicinc.com>
Signed-off-by: Jacek Lawrynowicz <jacek.lawrynowicz@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230202092114.2637452-5-stanislaw.gruszka@linux.intel.com