if_iwm - The iwm_prepare_card_hw() in iwm_attach() is only needed on …

…8K hw.

* Doing the iwm_prepare_card_hw() call in iwm_attach() only on Family 8000
  hardware matches the code in Linux iwlwifi.

* While there remove DEFAULT_MAX_TX_POWER definition which is unused, and
  has a value different from IWL_DEFAULT_MAX_TX_POWER in iwlwifi.

sys/dev/netif/iwm/if_iwm.c

@@ -1962,8 +1962,6 @@ enum nvm_sku_bits {
 #define IWM_NVM_RF_CFG_TX_ANT_MSK_8000(x)	((x >> 24) & 0xF)
 #define IWM_NVM_RF_CFG_RX_ANT_MSK_8000(x)	((x >> 28) & 0xF)
 
-#define DEFAULT_MAX_TX_POWER 16
-
 /**
  * enum iwm_nvm_channel_flags - channel flags in NVM
  * @IWM_NVM_CHANNEL_VALID: channel is usable for this SKU/geo
@@ -5923,19 +5921,18 @@ iwm_attach(device_t dev)
 	 * "dash" value). To keep hw_rev backwards compatible - we'll store it
 	 * in the old format.
 	 */
-	if (sc->cfg->device_family == IWM_DEVICE_FAMILY_8000)
-		sc->sc_hw_rev = (sc->sc_hw_rev & 0xfff0) |
-				(IWM_CSR_HW_REV_STEP(sc->sc_hw_rev << 2) << 2);
-
-	if (iwm_prepare_card_hw(sc) != 0) {
-		device_printf(dev, "could not initialize hardware\n");
-		goto fail;
-	}
-
 	if (sc->cfg->device_family == IWM_DEVICE_FAMILY_8000) {
 		int ret;
 		uint32_t hw_step;
 
+		sc->sc_hw_rev = (sc->sc_hw_rev & 0xfff0) |
+				(IWM_CSR_HW_REV_STEP(sc->sc_hw_rev << 2) << 2);
+
+		if (iwm_prepare_card_hw(sc) != 0) {
+			device_printf(dev, "could not initialize hardware\n");
+			goto fail;
+		}
+
 		/*
 		 * In order to recognize C step the driver should read the
 		 * chip version id located at the AUX bus MISC address.