e1000e: cleanup remaining strings split across multiple lines

Now that split strings generate checkpatch warnings (per Chapter 2 of
Documentation/CodingStyle to make it easier to grep the code for the
string) cleanup the remaining instances of them in the driver.

Signed-off-by: Bruce Allan <bruce.w.allan@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>