usb: common: usb-conn-gpio: Demote comment block which is clearly not kerneldoc

This block lacks a title and argument descriptions.

Fixes the following W=1 kernel build warning:

 drivers/usb/common/usb-conn-gpio.c:44: warning: Cannot understand  * "DEVICE" = VBUS and "HOST" = !ID, so we have:
 on line 44 - I thought it was a doc line

Cc: Chunfeng Yun <chunfeng.yun@mediatek.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Link: https://lore.kernel.org/r/20200702144625.2533530-5-lee.jones@linaro.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/common/usb-conn-gpio.c

@@ -40,7 +40,7 @@ struct usb_conn_info {
 	int vbus_irq;
 };
 
-/**
+/*
  * "DEVICE" = VBUS and "HOST" = !ID, so we have:
  * Both "DEVICE" and "HOST" can't be set as active at the same time
  * so if "HOST" is active (i.e. ID is 0)  we keep "DEVICE" inactive