LU-9859 libcfs: change libcfs_log_* functions to inline

The functions libcfs_log_return() and libcfs_log_goto() don't
exist in the native Linux client. We still need them for the
special OpenSFS debugging but we can change those functions
to simple inline routines since they are just wrappers
around libcfs_debug_msg().

Test-Parameters: trivial
Change-Id: I0e2b40feb18f9f1a1ffbda39756ab64308ea6439
Signed-off-by: James Simmons <jsimmons@infradead.org>
Reviewed-on: https://review.whamcloud.com/44581
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Aurelien Degremont <degremoa@amazon.com>
Reviewed-by: Arshad Hussain <arshad.hussain@aeoncomputing.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>