[lldb][Linux][ARM] Fix build after ptrace header removal (#219148)
f69fbd6415ab3a0743d14f0e345f9b61720ce187 / #218045 removed our own
ptrace header, which was fine elsewhere but on Arm we also included
asm/ptrace.h.
We don't have to though, and removing it fixes build errors like:
```
In file included from /buildbot/lldb-arm-ubuntu/llvmproject/lldb/source/Plugins/Process/Linux/NativeRegisterContextLinux_arm.cpp:31:
/usr/include/arm-linux-gnueabihf/sys/ptrace.h:74:3: error: expected identifier
74 | PTRACE_GETREGS = 12,
| ^
```
Which is because asm/ptrace.h has already defined PTRACE_GETREGS to 12.