[llvm-readobj] - Remove 3 excessive test cases.

This patch does the following:

1) Removes mips-options.test and the corresponding Inputs/mips-options.elf-mips64el binary:
This is a test that checks that --dynamic-table is able to print the DT_MIPS_OPTIONS tag.
We are testing it in dynamic-tags-machine-specific.test already.
(https://github.com/llvm/llvm-project/blob/master/llvm/test/tools/llvm-readobj/ELF/dynamic-tags-machine-specific.test#L235)

2) Removes mips-rld-map-rel.test and the corresponding Inputs/mips-rld-map-rel.elf-mipsel binary.
This is a test that checks that --dynamic-table is able to print the DT_MIPS_RLD_MAP_REL tag.
We are testing it in dynamic-tags-machine-specific.test already.
(https://github.com/llvm/llvm-project/blob/master/llvm/test/tools/llvm-readobj/ELF/dynamic-tags-machine-specific.test#L257)

3) Removes ppc64-glink.test test and the corresponding Inputs/ppc64.exe binary.
This is a test that checks that --dynamic-table is able to print the DT_PPC64_GLINK tag.
We are testing it in dynamic-tags-machine-specific.test already.
(https://github.com/llvm/llvm-project/blob/master/llvm/test/tools/llvm-readobj/ELF/dynamic-tags-machine-specific.test#L337)

Differential revision: https://reviews.llvm.org/D85515