phy: qualcomm: phy-qcom-eusb2-repeater: Support tune-res-fsdif prop

Support reading the FS Differential TX Output Resistance Tuning from
devicetree and writing the register, as required on some boards.

Reviewed-by: Abel Vesa <abel.vesa@linaro.org>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Signed-off-by: Luca Weiss <luca.weiss@fairphone.com>
Link: https://lore.kernel.org/r/20250709-sm7635-eusb-repeater-v2-2-b6eff075c097@fairphone.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

Author: lweiss-fairphone

drivers/phy/qualcomm/phy-qcom-eusb2-repeater.c

@@ -136,6 +136,9 @@ static int eusb2_repeater_init(struct phy *phy)
 	if (!of_property_read_u8(np, "qcom,tune-usb2-preem", &val))
 		regmap_write(regmap, base + EUSB2_TUNE_IUSB2, val);
 
+	if (!of_property_read_u8(np, "qcom,tune-res-fsdif", &val))
+		regmap_write(regmap, base + EUSB2_TUNE_RES_FSDIF, val);
+
 	/* Wait for status OK */
 	ret = regmap_read_poll_timeout(regmap, base + EUSB2_RPTR_STATUS, poll_val,
 				       poll_val & RPTR_OK, 10, 5);