soundwire: bus.h: repair kernel-doc comments

Use the correct struct names (i.e., correct typos).
Use the struct keyword for structs as required.

Prevents 5 warnings:

Warning: drivers/soundwire/bus.h:86 expecting prototype for struct
  sdw_btp_section. Prototype was for struct sdw_bpt_section instead
Warning: drivers/soundwire/bus.h:100 expecting prototype for struct
  sdw_btp_msg. Prototype was for struct sdw_bpt_msg instead
Warning: drivers/soundwire/bus.h:125 cannot understand function prototype:
  'struct sdw_port_runtime'
Warning: drivers/soundwire/bus.h:144 cannot understand function prototype:
  'struct sdw_slave_runtime'
Warning: drivers/soundwire/bus.h:165 cannot understand function prototype:
  'struct sdw_master_runtime'

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Link: https://patch.msgid.link/20260715030719.757781-1-rdunlap@infradead.org
Signed-off-by: Vinod Koul <vkoul@kernel.org>