[llvm] [BPF] Remove unnecessary BitCast operations (PR #131260)

[via llvm-commits]

yonghong-song wrote:

The test failures are from BOLT ([buildkite/github-pull-requests/linux-linux-x64](https://buildkite.com/llvm-project/github-pull-requests/builds/157202#0195929c-956a-42e9-b7de-a3fef6875012):
```
BOLT
BOLT.X86/icf-safe-icp.test
BOLT.X86/icf-safe-process-rela-data.test
BOLT.X86/icf-safe-test1.test
BOLT.X86/icf-safe-test2GlobalConstPtrNoPic.test
```
so it is not related to this patch.

https://github.com/llvm/llvm-project/pull/131260