soundwire: introduce BPT section

soundwire: introduce BPT section

Currently we send a BRA message with a start address with continuous
registers in a BPT stream. However, a codec may need to write different
register sections shortly. Introduce a register section in struct
sdw_btp_msg which contain register start address, length, and buffer.
This commit uses only 1 section for each BPT message. And we need to add
up all BPT section length and check if it reach maximum BPT bytes.
No function changes.

Signed-off-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Reviewed-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Tested-by: Shuming Fan <shumingf@realtek.com>
Link: https://patch.msgid.link/20251021094355.132943-2-yung-chuan.liao@linux.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>