Merge branch 'fix-implicit-sign-conversions-in-handshake-upcall'

Chuck Lever says:

====================
Fix implicit sign conversions in handshake upcall

An internal static analysis tool noticed some implicit sign
conversions for some of the arguments in the handshake upcall
protocol.
====================

Link: https://lore.kernel.org/r/169530154802.8905.2645661840284268222.stgit@oracle-102.nfsv4bat.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>