phy: qcom: m31: Remove unwanted qphy->vreg is NULL check

Fix the following Smatch complaint:
	drivers/phy/qualcomm/phy-qcom-m31.c:175 m31usb_phy_init()
	warn: variable dereferenced before check 'qphy->vreg' (see line 167)

drivers/phy/qualcomm/phy-qcom-m31.c
   166
   167		ret = regulator_enable(qphy->vreg);
                                       ^^^^^^^^^^
Unchecked dereference

   168		if (ret) {
   169			dev_err(&phy->dev, "failed to enable regulator, %d\n", ret);
   170			return ret;
   171		}
   172
   173		ret = clk_prepare_enable(qphy->clk);
   174		if (ret) {
   175			if (qphy->vreg)
                            ^^^^^^^^^^
Checked too late

   176				regulator_disable(qphy->vreg);
   177			dev_err(&phy->dev, "failed to enable cfg ahb clock, %d\n", ret);

Since the phy will not get registered if qphy->vreg is NULL,
this check is not needed.

Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/linux-phy/cbd26132-c624-44b7-a073-73222b287338@moroto.mountain/T/#u
Fixes: 08e49af5

 ("phy: qcom: Introduce M31 USB PHY driver")
Signed-off-by: Varadarajan Narayanan <quic_varada@quicinc.com>
Link: https://lore.kernel.org/r/1694069452-3794-1-git-send-email-quic_varada@quicinc.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>