Bluetooth: Fix sparse warning with btmrvl driver

This patch fixes the following sparse warning caused by a missing
declaration in the header file:

drivers/bluetooth/btmrvl_main.c:218:5: warning: symbol 'btmrvl_pscan_window_reporting' was not declared. Should it be static?
Signed-off-by: NJohan Hedberg <johan.hedberg@intel.com>
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>

drivers/bluetooth/btmrvl_drv.h

@@ -145,6 +145,7 @@ bool btmrvl_check_evtpkt(struct btmrvl_private *priv, struct sk_buff *skb);
 int btmrvl_process_event(struct btmrvl_private *priv, struct sk_buff *skb);
 
 int btmrvl_send_module_cfg_cmd(struct btmrvl_private *priv, u8 subcmd);
+int btmrvl_pscan_window_reporting(struct btmrvl_private *priv, u8 subcmd);
 int btmrvl_send_hscfg_cmd(struct btmrvl_private *priv);
 int btmrvl_enable_ps(struct btmrvl_private *priv);
 int btmrvl_prepare_command(struct btmrvl_private *priv);