[gdb/testsuite] Fix .debug_aranges in gdb.dwarf2/fission-loclists.S

When running test-case gdb.dwarf2/fission-loclists.exp, I noticed:
...
warning: Section .debug_aranges in fission-loclists has duplicate \
  debug_info_offset 0x8f, ignoring .debug_aranges.^M
...

Fix this by removing the duplicate .debug_aranges entry.

Tested on x86_64-linux.