LU-16785 build: Cleanup test for IS_ENCRYPTED macro

LU-16785 build: Cleanup test for IS_ENCRYPTED macro

Suppress warning when -Wunused-value is enabled.

Test-Parameters: trivial
Signed-off-by: Shaun Tancheff <shaun.tancheff@hpe.com>
Change-Id: Iec387286fd8499bb13f43c89e671d7d7aa0de9e1
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/50818
Tested-by: Maloo <maloo@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Reviewed-by: Sebastien Buisson <sbuisson@ddn.com>
Reviewed-by: Petros Koutoupis <petros.koutoupis@hpe.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>