LU-8191 libcfs: convert functions to static, removed function

LU-8191 libcfs: convert functions to static, removed function

Static analysis shows that a number of functions
could be made static. This patch declares several
functions in libcfs static.

Remove cfs_expr_list_values_free in string.c, since
it is not used.

A header was missing in param.c, causing a number of
functions to be missing declarations.

Lustre-change: https://review.whamcloud.com/51428
Lustre-commit: 067dfd8d2701572ebe7246726c14a6e72a78cb33

Test-Parameters: trivial
Signed-off-by: Timothy Day <timday@amazon.com>
Change-Id: Ia580881efa806bde49d532e5b2d8f5097f2294e0
Reviewed-on: https://review.whamcloud.com/c/ex/lustre-release/+/54620
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>