rtw88: fix sparse warnings for DPK

sparse warnings:
    drivers/net/wireless/realtek/rtw88/rtw8822c.c:2871:6: sparse:
sparse: symbol 'rtw8822c_dpk_cal_coef1' was not declared. Should it be
static?
    drivers/net/wireless/realtek/rtw88/rtw8822c.c:3112:6: sparse:
sparse: symbol 'rtw8822c_dpk_track' was not declared. Should it be
static?

Fixes: 5227c2ee ("rtw88: 8822c: add SW DPK support")
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Yan-Hsuan Chuang <yhchuang@realtek.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/realtek/rtw88/rtw8822c.c

@@ -2970,7 +2970,7 @@ static void rtw8822c_dpk_cal_gs(struct rtw_dev *rtwdev, u8 path)
 	dpk_info->dpk_gs[path] = tmp_gs;
 }
 
-void rtw8822c_dpk_cal_coef1(struct rtw_dev *rtwdev)
+static void rtw8822c_dpk_cal_coef1(struct rtw_dev *rtwdev)
 {
 	struct rtw_dpk_info *dpk_info = &rtwdev->dm_info.dpk_info;
 	u32 offset[DPK_RF_PATH_NUM] = {0, 0x58};
@@ -3211,7 +3211,7 @@ static void rtw8822c_phy_calibration(struct rtw_dev *rtwdev)
 	rtw8822c_do_dpk(rtwdev);
 }
 
-void rtw8822c_dpk_track(struct rtw_dev *rtwdev)
+static void rtw8822c_dpk_track(struct rtw_dev *rtwdev)
 {
 	struct rtw_dpk_info *dpk_info = &rtwdev->dm_info.dpk_info;
 	u8 path;