e1000e: specify max supported frame size in adapter struct

By putting the maximum frame size supported by the hardware into the
adapter structure, the change_mtu entry point function can be cleaned
up of checks for all the different max frame sizes supported by

Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/e1000e/e1000.h b/drivers/net/e1000e/e1000.h
index f37360a..b9dc612 100644
--- a/drivers/net/e1000e/e1000.h
+++ b/drivers/net/e1000e/e1000.h
@@ -96,6 +96,8 @@
 /* Number of packet split data buffers (not including the header buffer) */
 #define PS_PAGE_BUFFERS			(MAX_PS_BUFFERS - 1)
 
+#define DEFAULT_JUMBO			9234
+
 enum e1000_boards {
 	board_82571,
 	board_82572,
@@ -293,6 +295,7 @@
 	u32 eeprom_wol;
 	u32 wol;
 	u32 pba;
+	u32 max_hw_frame_size;
 
 	bool fc_autoneg;
 
@@ -309,6 +312,7 @@
 	unsigned int		flags;
 	unsigned int            flags2;
 	u32			pba;
+	u32			max_hw_frame_size;
 	s32			(*get_variants)(struct e1000_adapter *);
 	struct e1000_mac_operations *mac_ops;
 	struct e1000_phy_operations *phy_ops;