scripts/check_format: fix an escaping issue.

Some older versions of Fedora require putting the git grep contents
in quotes before feeding to the while loop.

Change-Id: I649d5520f4a8c0a903aed2e2dda337e91b5b596e
Signed-off-by: chenlo2x <longx.o.chen@intel.com>
Reviewed-on: https://review.gerrithub.io/428332
Reviewed-by: Jim Harris <james.r.harris@intel.com>
Reviewed-by: Shuhei Matsumoto <shuhei.matsumoto.xt@hitachi.com>
Reviewed-by: Liang Yan <liang.z.yan@intel.com>
Reviewed-by: Changpeng Liu <changpeng.liu@intel.com>
Chandler-Test-Pool: SPDK Automated Test System <sys_sgsw@intel.com>
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>

scripts/check_format.sh

@@ -45,7 +45,7 @@ while read -r perm _res0 _res1 path; do
 		;;
 	esac
 
-done <<< $(git grep -I --name-only --untracked -e . | git ls-files -s)
+done <<< "$(git grep -I --name-only --untracked -e . | git ls-files -s)"
 
 if [ $rc -eq 0 ]; then
 	echo " OK"