phy: intel: fix enum type mismatch warning

clang points out that a local variable is initialized with
an enum value of the wrong type:

drivers/phy/intel/phy-intel-combo.c:202:34: error: implicit conversion from enumeration type 'enum intel_phy_mode' to different enumeration type 'enum intel_combo_mode' [-Werror,-Wenum-conversion]
enum intel_combo_mode cb_mode = PHY_PCIE_MODE;
~~~~~~~ ^~~~~~~~~~~~~

>From reading the code, it seems that this was not only the
wrong type, but not even supposed to be a code path that can
happen in practice.

Change the code to have no default phy mode but instead return an
error for invalid input.

Fixes: ac0a95a3ea78 ("phy: intel: Add driver support for ComboPhy")
Signed-off-by: Arnd Bergmann <[e-mail]>
Reviewed-by: Dilip Kota <[e-mail]>
Reviewed-by: Nathan Chancellor <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Vinod Koul <[e-mail]>

drivers/phy/intel/phy-intel-combo.c

···
 
 static int intel_cbphy_set_mode(struct intel_combo_phy *cbphy)
 {
-	enum intel_combo_mode cb_mode = PHY_PCIE_MODE;
+	enum intel_combo_mode cb_mode;
 	enum aggregated_mode aggr = cbphy->aggr_mode;
 	struct device *dev = cbphy->dev;
 	enum intel_phy_mode mode;
···
 
 		cb_mode = SATA0_SATA1_MODE;
 		break;
+	default:
+		return -EINVAL;
 	}
 
 	ret = regmap_write(cbphy->hsiocfg, REG_COMBO_MODE(cbphy->bid), cb_mode);