Remove obsolete BIOS workaround from 2002

In the changelog of Debian lilo 22.2-3.1 (from 2002-05-10) was noted:

  * This upstream version uses int15,0xe820 to fetch the memory map.
    However, sufficiently many systems don't implement this interrupt
    correctly.  We avoid the errant code for now.  The next upstream
    release fixes this problem for real.  Note to Russell: this patch
    must be removed for the next upstream release.

Unfortunately nobody had remembered to this note and removed this 
workaround with the new upstream release. But the upstream release
22.3 (from 2002-10-19) of have the following note in its CHANGES: 

    - Compensate for buggy BIOS in int 15h, fn E820h call to avoid
      overlapping memory areas

Now I remove this very old workaround because it is obsolete since
May 2002!
