nfsd: declare several functions of nfs4callback as static
nfsd: declare several functions of nfs4callback as static

setup_callback_client(), nfsd4_release_cb() and nfsd4_process_cb_update()
do not have users outside the translation unit. Let's declare it as
static.

Signed-off-by: Kirill A. Shutemov <9b153e80bc985b32d577460a8a24e398d4182978@shutemov.name>
Signed-off-by: J. Bruce Fields <51738506c1b2ccb0761f23bdc612c93babf738ea@redhat.com>

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