perf evsel: Rename evsel__increase_rlimit to rlimit__increase_nofile

perf evsel: Rename evsel__increase_rlimit to rlimit__increase_nofile

evsel__increase_rlimit() helper does nothing with evsel, and description
of the functionality is inaccurate, rename it and move to util/rlimit.c.

By the way, fix a checkppatch warning about misplaced license tag:

  WARNING: Misplaced SPDX-License-Identifier tag - use line 1 instead
  #160: FILE: tools/perf/util/rlimit.h:3:
  /* SPDX-License-Identifier: LGPL-2.1 */

No functional change.

Signed-off-by: Yang Jihong <yangjihong1@huawei.com>
Link: https://lore.kernel.org/r/20231023033144.1011896-1-yangjihong1@huawei.com
Signed-off-by: Namhyung Kim <namhyung@kernel.org>