usb: chipidea: otg: Fix formatting and missing documentation issues

Fixes the following W=1 kernel build warning(s):

 drivers/usb/chipidea/otg.c:25: warning: This comment starts with '/**', but isn't a kernel-doc comment. Refer Documentation/doc-guide/kernel-doc.rst
 drivers/usb/chipidea/otg.c:78: warning: This comment starts with '/**', but isn't a kernel-doc comment. Refer Documentation/doc-guide/kernel-doc.rst
 drivers/usb/chipidea/otg.c:143: warning: This comment starts with '/**', but isn't a kernel-doc comment. Refer Documentation/doc-guide/kernel-doc.rst

Cc: Peter Chen <peter.chen@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-usb@vger.kernel.org
Acked-by: Peter Chen <peter.chen@kernel.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Link: https://lore.kernel.org/r/20210526130037.856068-15-lee.jones@linaro.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/chipidea/otg.c

@@ -22,7 +22,7 @@
 #include "otg_fsm.h"
 
 /**
- * hw_read_otgsc returns otgsc register bits value.
+ * hw_read_otgsc - returns otgsc register bits value.
  * @ci: the controller
  * @mask: bitfield mask
  */
@@ -75,7 +75,7 @@ u32 hw_read_otgsc(struct ci_hdrc *ci, u32 mask)
 }
 
 /**
- * hw_write_otgsc updates target bits of OTGSC register.
+ * hw_write_otgsc - updates target bits of OTGSC register.
  * @ci: the controller
  * @mask: bitfield mask
  * @data: to be written
@@ -140,8 +140,9 @@ void ci_handle_vbus_change(struct ci_hdrc *ci)
 }
 
 /**
- * When we switch to device mode, the vbus value should be lower
- * than OTGSC_BSV before connecting to host.
+ * hw_wait_vbus_lower_bsv - When we switch to device mode, the vbus value
+ *                          should be lower than OTGSC_BSV before connecting
+ *                          to host.
  *
  * @ci: the controller
  *