Tools: hv: address compiler warnings for hv_kvp_daemon.c

This patch addresses two types of compiler warnings:
... warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
and
... warning: pointer targets in passing argument N of .kvp_.... differ in signedness [-Wpointer-sign]

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>