staging: r8192U_core: Do not use kernel-doc formatting for !kernel-doc headers

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

 drivers/staging/rtl8192u/r8192U_core.c:3714: warning: Function parameter or member 'dev' not described in 'UpdateRxPktTimeStamp8190'
 drivers/staging/rtl8192u/r8192U_core.c:3714: warning: Function parameter or member 'stats' not described in 'UpdateRxPktTimeStamp8190'
 drivers/staging/rtl8192u/r8192U_core.c:3714: warning: expecting prototype for Function(). Prototype was for UpdateRxPktTimeStamp8190() instead
 drivers/staging/rtl8192u/r8192U_core.c:4314: warning: Function parameter or member 'dev' not described in 'UpdateReceivedRateHistogramStatistics8190'
 drivers/staging/rtl8192u/r8192U_core.c:4314: warning: Function parameter or member 'stats' not described in 'UpdateReceivedRateHistogramStatistics8190'
 drivers/staging/rtl8192u/r8192U_core.c:4314: warning: expecting prototype for Function(). Prototype was for UpdateReceivedRateHistogramStatistics8190() instead

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Andrea Merello <andrea.merello@gmail.com>
Cc: Jerry chuang <wlanfae@realtek.com>
Cc: linux-staging@lists.linux.dev
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Link: https://lore.kernel.org/r/20210414181129.1628598-5-lee.jones@linaro.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/rtl8192u/r8192U_core.c

@@ -3694,7 +3694,7 @@ static u8 HwRateToMRate90(bool bIsHT, u8 rate)
 	return ret_rate;
 }
 
-/**
+/*
  * Function:     UpdateRxPktTimeStamp
  * Overview:     Record the TSF time stamp when receiving a packet
  *
@@ -4294,7 +4294,7 @@ static void TranslateRxSignalStuff819xUsb(struct sk_buff *skb,
 	rtl8192_record_rxdesc_forlateruse(pstats, &previous_stats);
 }
 
-/**
+/*
  * Function:	UpdateReceivedRateHistogramStatistics
  * Overview:	Record the received data rate
  *