packaging: Fix kernel-confidential name

We've been passing "kernel" instead of "kernel-confidential", which
would make the scripts used to build the kernel modules not work as
expected.

Signed-off-by: Fabiano Fidêncio <fabiano.fidencio@intel.com>
Reported-by: Zvonko Kaiser <zkaiser@nvidia.com>

tools/packaging/kata-deploy/local-build/kata-deploy-binaries.sh

@@ -362,7 +362,7 @@ install_kernel_confidential() {
 
 	install_kernel_helper \
 		"assets.kernel.confidential.version" \
-		"kernel" \
+		"kernel-confidential" \
 		"-x confidential -u ${kernel_url}"
 }