Revert "sched/headers: Move 'struct sched_param' out of uapi, to work around glibc/musl breakage"

This reverts commit 654f3294 which is
commit d844fe65 upstream.

It breaks the Android kernel abi and can be brought back in the future
in an abi-safe way if it is really needed.

Bug: 161946584
Change-Id: Ied1aad55ade1751af127b99859c6dbc25c153179
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>