staging: vt6655: Remove an unused function prototype

Remove an unused function prototype as there is no such function in the
kernel tree.
Signed-off-by: Madhumitha Prabakaran <madhumithabiw@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/vt6655/mac.h

@@ -887,8 +887,6 @@ void MACvSetShortRetryLimit(struct vnt_private *priv,
 			    unsigned char byRetryLimit);
 
 void MACvSetLongRetryLimit(struct vnt_private *priv, unsigned char byRetryLimit);
-void MACvGetLongRetryLimit(struct vnt_private *priv,
-			   unsigned char *pbyRetryLimit);
 
 void MACvSetLoopbackMode(struct vnt_private *priv, unsigned char byLoopbackMode);