ceph: suppress shellcheck warnings
ceph: suppress shellcheck warnings

Suppress the following shellcheck warnings.

https://github.com/koalaman/shellcheck/wiki/SC2018
https://github.com/koalaman/shellcheck/wiki/SC2019
https://github.com/koalaman/shellcheck/wiki/SC2021

Signed-off-by: Satoru Takeuchi <0be322b419f8cd46ee75447832ef0476dff222bc@gmail.com>

rook/nfs,rook/rook,rook/rook,rook/rook,rook/rook,rook/nfs,rook/nfs,rook/rook