timer_create will fail with invalid error code

[Thadeu Lima de Souza Cascardo]

[Impact]
On some OpenPower systems, RTC does not support set_alarm, and timer_create(CLOCK_REALTIME_ALARM, ...) will fail with ENOTSUPP instead of EOPNOTSUPP. This will break some regression testing that expects the later value.

[Test cases]
Run LTP syscalls regression testing, which we do before releasing kernels.

[Regression potential]
This should not break any userspace, as none should be using/expecting ENOTSUPP for any call. In order to do so, they would have to go out of their way as it's not defined on libc headers.

[Thadeu Lima de Souza Cascardo (cascardo)]

https://<email address hidden>/T/#u

[Thadeu Lima de Souza Cascardo (cascardo)]

This has been applied as part of stable upstream fixes.

[Brian Murray (brian-murray)]

The Eoan Ermine has reached end of life, so this bug will not be fixed for that release