Staging: hv: mouse_drv: Fix a sparse warning

Most of the sparse warnings in the hv code are from the base kernel.
This patch fixes the only sparse related issue in the Hyper-V coode.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: Abhishek Kane <v-abkane@microsoft.com>
Signed-off-by: Hank Janssen <hjanssen@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/staging/hv/hv_mouse.c

@@ -489,7 +489,7 @@ static void mousevsc_on_channel_callback(void *context)
 
 	u32 bytes_recvd;
 	u64 req_id;
-	unsigned char packet[packetSize];
+	unsigned char packet[0x100];
 	struct vmpacket_descriptor *desc;
 	unsigned char	*buffer = packet;
 	int	bufferlen = packetSize;