LU-18141 mdt: don't check for NULL before free'ing

LU-18141 mdt: don't check for NULL before free'ing

The common free'ing macros already check for NULL,
so we don't need to explicitly check this beforehand.

The patch has been generated with the coccinelle script below.

@@
expression E;
@@
- if (E != NULL)
(
  OBD_FREE_PTR(E);
|
  OBD_FREE(E, ...);
|
  LIBCFS_FREE(E, ...);
|
  CFS_FREE_PTR(E);
|
  CFS_FREE_PTR_ARRAY(E, ...);
)

Test-Parameters: trivial
Signed-off-by: Timothy Day <timday@amazon.com>
Change-Id: Id08fd059dbc4fcb3508497bdd04c6b00035ff91e
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/56045
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: jsimmons <jsimmons@infradead.org>
Reviewed-by: Arshad Hussain <arshad.hussain@aeoncomputing.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>