LU-18538 ldlm: use bitmap for NS flags

LU-18538 ldlm: use bitmap for NS flags

Use a bitmap for namespace flags in LDLM. Consolidate two
bit fields into a single bitmap. This is more in line with
Linux kernel style and more correct.

Fixes: 70b9dc5 ("LU-17812 ldlm: stack trace log for LDLM error")
Fixes: 3d4b5da ("LU-11518 ldlm: cancel LRU improvement")
Signed-off-by: Timothy Day <timday@amazon.com>
Change-Id: I50dd21d064147db1a93edb2e582db29c26b1c211
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/57386
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>