[llvm-readobj][test] - Remove amdgpu-elf-definitions.test

[grimar]

Summary

amdgpu-elf-definitions.test is a file that tests
Format, 'OS/ABI' and 'Machine' fields printed for EM_AMDGPU.
It uses a precompiled object.

It is not needed to have it, because:

1. We already test formats in file-header-format.test + llvm/unittests/Object/ELFObjectFileTest.cpp.
2. We test 'OS/ABI' in file-header-os-abi.test for all possible values.
3. We test machine types in file-header-machine-types.test

In addition we have amdgpu-elf-headers.test which tests EM_AMDGPU specific flags. I.e.
it also tests the fact that llvm-readobj/elf are able to dump such objects.

This patch removes the test case and the corresponding binary.

[jhenderson]

LGTM.

llvm/test/tools/llvm-readobj/ELF/amdgpu-elf-definitions.test

-# RUN: llvm-readobj --file-headers -l -S --symbols %p/Inputs/trivial.obj.elf-amdhsa-gfx803 | FileCheck %s
-
-# CHECK: Format: elf64-amdgpu
-# CHECK: Arch: unknown
-# CHECK: ElfHeader {
-# CHECK:   Ident {
-# CHECK:     OS/ABI: AMDGPU_HSA (0x40)
-# CHECK:     ABIVersion: 0
-# CHECK:   }
-# CHECK:   Machine: EM_AMDGPU (0xE0)
-# CHECK: }