usb: dwc3: st: fix incorrect kernel-doc comment syntax in file

The opening comment mark '/**' is used for highlighting the beginning of
kernel-doc comments.
The header for drivers/usb/dwc3/dwc3-st.c follows this syntax, but the
content inside does not comply with kernel-doc.

This line was probably not meant for kernel-doc parsing, but is parsed
due to the presence of kernel-doc like comment syntax(i.e, '/**'), which
causes unexpected warning from kernel-doc:
"warning: expecting prototype for dwc3(). Prototype was for CLKRST_CTRL() instead"

Provide a simple fix by replacing this occurrence with general comment
format, i.e. '/*', to prevent kernel-doc from parsing it.
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Aditya Srivastava <yashsri421@gmail.com>
Link: https://lore.kernel.org/r/20210329132014.24304-1-yashsri421@gmail.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/dwc3/dwc3-st.c

 // SPDX-License-Identifier: GPL-2.0+
-/**
+/*
  * dwc3-st.c Support for dwc3 platform devices on ST Microelectronics platforms
  *
  * This is a small driver for the dwc3 to provide the glue logic