Revert "perf/core: Add a new read format to get a number of lost samples"

This reverts commit 00f8c6dc which is
commit 119a784c 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: I9f973774a99437a3dcfecf32eff8e7ddcfd418ed
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>