nfsd4: fix sessions slotid wraparound logic
nfsd4: fix sessions slotid wraparound logic

From RFC 5661 2.10.6.1: "If the previous sequence ID was 0xFFFFFFFF,
then the next request for the slot MUST have the sequence ID set to
zero."

While we're there, delete some redundant comments.

Signed-off-by: J. Bruce Fields <51738506c1b2ccb0761f23bdc612c93babf738ea@redhat.com>

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