media: pulse8-cec: set tx_done_status for transmit_done status

Instead of translating work_result to a transmit_done status
in pulse8_irq_work_handler(), pass the CEC_TX_STATUS via a
new tx_done_status field.

Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>