igb: Fix for failure to init on some 82576 devices.

Move nvm invalid size check to before size assigned by mac_type for
82575 and later parts in get_invariants function.  This fixes a problem
found on some 82576 devices where the part will not initialize because
the nvm_read function pointer ends up getting assigned to the incorrect
function.

Reported By: Stefan Assmann <sassmann@redhat.com>
Signed-off-by: Carolyn Wyborny <carolyn.wyborny@intel.com>
Tested-by: Jeff Pieper <jeffrey.e.pieper@intel.com>
Signed-off-by: Peter P Waskiewicz Jr <peter.p.waskiewicz.jr@intel.com>

drivers/net/ethernet/intel/igb/e1000_82575.c

@@ -254,6 +254,14 @@ static s32 igb_get_invariants_82575(struct e1000_hw *hw)
 	 */
 	size += NVM_WORD_SIZE_BASE_SHIFT;
 
+	/*
+	 * Check for invalid size
+	 */
+	if ((hw->mac.type == e1000_82576) && (size > 15)) {
+		pr_notice("The NVM size is not valid, defaulting to 32K\n");
+		size = 15;
+	}
+
 	nvm->word_size = 1 << size;
 	if (hw->mac.type < e1000_i210) {
 		nvm->opcode_bits        = 8;
@@ -281,14 +289,6 @@ static s32 igb_get_invariants_82575(struct e1000_hw *hw)
 	} else
 		nvm->type = e1000_nvm_flash_hw;
 
-	/*
-	 * Check for invalid size
-	 */
-	if ((hw->mac.type == e1000_82576) && (size > 15)) {
-		pr_notice("The NVM size is not valid, defaulting to 32K\n");
-		size = 15;
-	}
-
 	/* NVM Function Pointers */
 	switch (hw->mac.type) {
 	case e1000_82580: