FIELD_PREP() does not replace the bits so it is not apt in case where we
modify a register.

Use u32p_replace_bits() instead.

Fixes: 3cf25d63 ("soundwire: cadence: use FIELD_{GET|PREP}")
Tested-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Link: https://lore.kernel.org/r/20200917120146.1780323-2-vkoul@kernel.orgSigned-off-by: Vinod Koul <vkoul@kernel.org>