net: smsc95xx: Use correct get_unaligned functions

The __get_unaligned_le* functions may not be declared on all platforms.
Instead, get_unaligned_le* should be used. On many platforms both of
these are the same function.

Signed-off-by: Chris Packham <judge.packham@gmail.com>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>