soundwire: bus: Remove now outdated comments on no_pm IO

Things have moved more towards end drivers using the no_pm versions of
the IO functions. See commits:

commit 167790ab ("soundwire: export sdw_write/read_no_pm functions")
commit 62dc9f3f ("soundwire: bus: export sdw_nwrite_no_pm and
                      sdw_nread_no_pm functions")

As such this comment is now misleading, so remove it.

Signed-off-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Link: https://lore.kernel.org/r/20230322164948.566962-1-ckeepax@opensource.cirrus.com


Signed-off-by: Vinod Koul <vkoul@kernel.org>