tools: ynl: fix header path for nfsd

The makefile dependency is trying to include the wrong header:

<command-line>: fatal error: ../../../../include/uapi//linux/nfsd.h: No such file or directory

The guard also looks wrong.

Fixes: f14122b ("tools: ynl: Add source files for nfsd netlink protocol")
Reviewed-by: Chuck Lever <chuck.lever@oracle.com>
Link: https://lore.kernel.org/r/20231123030624.1611925-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

tools/net/ynl/Makefile.deps

@@ -18,4 +18,4 @@ CFLAGS_devlink:=$(call get_hdr_inc,_LINUX_DEVLINK_H_,devlink.h)
 CFLAGS_ethtool:=$(call get_hdr_inc,_LINUX_ETHTOOL_NETLINK_H_,ethtool_netlink.h)
 CFLAGS_handshake:=$(call get_hdr_inc,_LINUX_HANDSHAKE_H,handshake.h)
 CFLAGS_netdev:=$(call get_hdr_inc,_LINUX_NETDEV_H,netdev.h)
-CFLAGS_nfsd:=$(call get_hdr_inc,_LINUX_NFSD_H,nfsd.h)
+CFLAGS_nfsd:=$(call get_hdr_inc,_LINUX_NFSD_NETLINK_H,nfsd_netlink.h)