nfsd4: lockt, release_lockowner should renew clients
nfsd4: lockt, release_lockowner should renew clients

Fix nfsd4_lockt and release_lockowner to lookup the referenced client,
so that it can renew it, or correctly return "expired", as appropriate.

Also share some code while we're here.

Reported-by: Frank Filz <bea13b40ec72713ddcfa070741018e0feab937d4@us.ibm.com>
Signed-off-by: J. Bruce Fields <51738506c1b2ccb0761f23bdc612c93babf738ea@redhat.com>

KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs