soundwire: rename 'freq' fields

Rename all fields with 'freq' as 'clk_freq' to follow the MIPI
specification and avoid confusion between bus clock and audio clocks.

No functionality change.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Vinod Koul <vkoul@kernel.org>