script: make gen_kobject_list.py compatible with dwarf-2

This issuse is found in arch/arc's memory domain api support.
For arc, dwarf-2 is used to keep compatible with synopsys metaware
mdb debugger. However, the gen_kobject_list.py cannot generate the
correct information from dwarf-2, because loc.form's value is
DW_FORM_block1.

If dwarf-4 is adopted, there is no issuse.

Other arch and tools may use dwarf-2 and face the same issuse, so
this commit is created.

Signed-off-by: Wayne Ren <wei.ren@synopsys.com>