soundwire: qcom: remove unused rd_fifo_depth

remove read fifo depth field parsing logic, as rd_fifo_depth is never
used in the driver. Cleaning this up would benefit when adding new
variant support which includes adding variant fields for rd_fifo_depth.

ex: Glymur has this rd_fifo_depth register fields changed from v2.x

Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@oss.qualcomm.com>
Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
Tested-by: Alexey Klimov <alexey.klimov@linaro.org> # sm8550
Link: https://patch.msgid.link/20250912083225.228778-3-srinivas.kandagatla@oss.qualcomm.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

Author: Srinivas Kandagatla

drivers/soundwire/qcom.c

@@ -209,7 +209,6 @@ struct qcom_swrm_ctrl {
 	int (*reg_write)(struct qcom_swrm_ctrl *ctrl, int reg, int val);
 	u32 slave_status;
 	u32 wr_fifo_depth;
-	u32 rd_fifo_depth;
 	bool clock_stop_not_supported;
 };
 
@@ -898,7 +897,6 @@ static int qcom_swrm_init(struct qcom_swrm_ctrl *ctrl)
 	swrm_wait_for_frame_gen_enabled(ctrl);
 	ctrl->slave_status = 0;
 	ctrl->reg_read(ctrl, SWRM_COMP_PARAMS, &val);
-	ctrl->rd_fifo_depth = FIELD_GET(SWRM_COMP_PARAMS_RD_FIFO_DEPTH, val);
 	ctrl->wr_fifo_depth = FIELD_GET(SWRM_COMP_PARAMS_WR_FIFO_DEPTH, val);
 
 	return 0;