mmc: sdhci-pci-gli: Fix build error unused-function

If CONFIG_PM is not set.

make ARCH=x86_64 CROSS_COMPILE=x86_64-linux-gnu-, will be failed, like this:

drivers/mmc/host/sdhci-pci-gli.c:834:13: error: ‘gl9763e_set_low_power_negotiation’ defined but not used [-Werror=unused-function]
 static void gl9763e_set_low_power_negotiation(struct sdhci_pci_slot *slot, bool enable)
             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors
make[3]: *** [drivers/mmc/host/sdhci-pci-gli.o] Error 1

To fix building warning, wrap all related code with CONFIG_PM.
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Ren Zhijie <renzhijie2@huawei.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Link: https://lore.kernel.org/r/20220619104712.125364-1-renzhijie2@huawei.comSigned-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/host/sdhci-pci-gli.c

@@ -831,31 +831,6 @@ static void sdhci_gl9763e_dumpregs(struct mmc_host *mmc)
 	sdhci_dumpregs(mmc_priv(mmc));
 }
 
-static void gl9763e_set_low_power_negotiation(struct sdhci_pci_slot *slot, bool enable)
-{
-	struct pci_dev *pdev = slot->chip->pdev;
-	u32 value;
-
-	pci_read_config_dword(pdev, PCIE_GLI_9763E_VHS, &value);
-	value &= ~GLI_9763E_VHS_REV;
-	value |= FIELD_PREP(GLI_9763E_VHS_REV, GLI_9763E_VHS_REV_W);
-	pci_write_config_dword(pdev, PCIE_GLI_9763E_VHS, value);
-
-	pci_read_config_dword(pdev, PCIE_GLI_9763E_CFG, &value);
-
-	if (enable)
-		value &= ~GLI_9763E_CFG_LPSN_DIS;
-	else
-		value |= GLI_9763E_CFG_LPSN_DIS;
-
-	pci_write_config_dword(pdev, PCIE_GLI_9763E_CFG, value);
-
-	pci_read_config_dword(pdev, PCIE_GLI_9763E_VHS, &value);
-	value &= ~GLI_9763E_VHS_REV;
-	value |= FIELD_PREP(GLI_9763E_VHS_REV, GLI_9763E_VHS_REV_R);
-	pci_write_config_dword(pdev, PCIE_GLI_9763E_VHS, value);
-}
-
 static void sdhci_gl9763e_cqe_pre_enable(struct mmc_host *mmc)
 {
 	struct cqhci_host *cq_host = mmc->cqe_private;
@@ -991,6 +966,31 @@ static void gli_set_gl9763e(struct sdhci_pci_slot *slot)
 }
 
 #ifdef CONFIG_PM
+static void gl9763e_set_low_power_negotiation(struct sdhci_pci_slot *slot, bool enable)
+{
+	struct pci_dev *pdev = slot->chip->pdev;
+	u32 value;
+
+	pci_read_config_dword(pdev, PCIE_GLI_9763E_VHS, &value);
+	value &= ~GLI_9763E_VHS_REV;
+	value |= FIELD_PREP(GLI_9763E_VHS_REV, GLI_9763E_VHS_REV_W);
+	pci_write_config_dword(pdev, PCIE_GLI_9763E_VHS, value);
+
+	pci_read_config_dword(pdev, PCIE_GLI_9763E_CFG, &value);
+
+	if (enable)
+		value &= ~GLI_9763E_CFG_LPSN_DIS;
+	else
+		value |= GLI_9763E_CFG_LPSN_DIS;
+
+	pci_write_config_dword(pdev, PCIE_GLI_9763E_CFG, value);
+
+	pci_read_config_dword(pdev, PCIE_GLI_9763E_VHS, &value);
+	value &= ~GLI_9763E_VHS_REV;
+	value |= FIELD_PREP(GLI_9763E_VHS_REV, GLI_9763E_VHS_REV_R);
+	pci_write_config_dword(pdev, PCIE_GLI_9763E_VHS, value);
+}
+
 static int gl9763e_runtime_suspend(struct sdhci_pci_chip *chip)
 {
 	struct sdhci_pci_slot *slot = chip->slots[0];