kmod: explicitly define host-kmod dependencies

So we don't end up pulling in host-busybox (which doesn't exist) if
KMOD_TOOLS is enabled.

Reported-by: Sagaert Johan <sagaert.johan@skynet.be>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

package/kmod/kmod.mk

@@ -9,6 +9,7 @@ KMOD_SOURCE = kmod-$(KMOD_VERSION).tar.xz
 KMOD_SITE = $(BR2_KERNEL_MIRROR)/linux/utils/kernel/kmod/
 KMOD_INSTALL_STAGING = YES
 KMOD_DEPENDENCIES = host-pkgconf
+HOST_KMOD_DEPENDENCIES = host-pkgconf
 
 # Some patches are touching configure.ac
 KMOD_AUTORECONF = YES