HID: intel-ish-hid: remove redundant variable num_frags

Variable num_frags is being assigned but is never used hence it is
redundant and can be removed.

Cleans up clang warning:
warning: variable 'num_frags' set but not used [-Wunused-but-set-variable]
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

drivers/hid/intel-ish-hid/ishtp/hbm.c

@@ -298,7 +298,6 @@ int ishtp_hbm_cl_flow_control_req(struct ishtp_device *dev,
 	struct ishtp_msg_hdr *ishtp_hdr = &hdr;
 	const size_t len = sizeof(struct hbm_flow_control);
 	int	rv;
-	unsigned int	num_frags;
 	unsigned long	flags;
 
 	spin_lock_irqsave(&cl->fc_spinlock, flags);
@@ -314,7 +313,6 @@ int ishtp_hbm_cl_flow_control_req(struct ishtp_device *dev,
 		return	0;
 	}
 
-	num_frags = cl->recv_msg_num_frags;
 	cl->recv_msg_num_frags = 0;
 
 	rv = ishtp_write_message(dev, ishtp_hdr, data);