phy: qualcomm: ipq806x-usb: Fix kernel-doc style

phy: qualcomm: ipq806x-usb: Fix kernel-doc style

The functions are documented but there were style issues, so fix
the style and add missing description for phy_dwc3

drivers/phy/qualcomm/phy-qcom-ipq806x-usb.c:130:
drivers/phy/qualcomm/phy-qcom-ipq806x-usb.c:174:
drivers/phy/qualcomm/phy-qcom-ipq806x-usb.c:212: warning:
This comment starts with '/**', but isn't a kernel-doc comment.
Refer Documentation/doc-guide/kernel-doc.rst

Reviewed-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20211120061531.410771-1-vkoul@kernel.org
Signed-off-by: Vinod Koul <vkoul@kernel.org>