e100: fix length calculation in e100_get_regs_len

commit abf9b902 ("e100: cleanup unneeded math") tried to simplify
e100_get_regs_len and remove a double 'divide and then multiply'
calculation that the e100_reg_regs_len function did.

This change broke the size calculation entirely as it failed to account
for the fact that the numbered registers are actually 4 bytes wide and
not 1 byte. This resulted in a significant under allocation of the
register buffer used by e100_get_regs.

Fix this by properly multiplying the register count by u32 first before
adding the size of the dump buffer.

Fixes: abf9b902 ("e100: cleanup unneeded math")
Reported-by: Felicitas Hetzelt <felicitashetzelt@gmail.com>
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

drivers/net/ethernet/intel/e100.c

@@ -2441,7 +2441,11 @@ static void e100_get_drvinfo(struct net_device *netdev,
 static int e100_get_regs_len(struct net_device *netdev)
 {
 	struct nic *nic = netdev_priv(netdev);
-	return 1 + E100_PHY_REGS + sizeof(nic->mem->dump_buf);
+
+	/* We know the number of registers, and the size of the dump buffer.
+	 * Calculate the total size in bytes.
+	 */
+	return (1 + E100_PHY_REGS) * sizeof(u32) + sizeof(nic->mem->dump_buf);
 }
 
 static void e100_get_regs(struct net_device *netdev,