Fix kernel-devel package name for rhel8

When using `wget`, the package name must contain the architecture too.
By redefining the `kernel_source_package_version` we're avoiding to `chomp` the architecture from kernel version.

Then, use `node['kernel']['machine']` rather than `uname -m`.

### Tests

Verified that `dnf install` is working on both the cases when passing architecture.

### References

* https://github.com/chef/ohai/blob/17-stable/lib/ohai/plugins/kernel.rb#L34

Signed-off-by: Enrico Usai <usai@amazon.com>

Author: Enrico Usai

cookbooks/aws-parallelcluster-platform/resources/install_packages/install_packages_rocky8.rb

@@ -28,17 +28,20 @@
     # try to install kernel source for a specific release version
     dnf install -y ${package} --releasever #{node['platform_version']}
     if [ $? -ne 0 ]; then
-      set -e
       # Previous releases are moved into a vault area once a new minor release version is available for at least a week.
       # https://wiki.rockylinux.org/rocky/repo/#notes-on-devel
-      wget https://dl.rockylinux.org/vault/rocky/#{node['platform_version']}/BaseOS/$(uname -m)/os/Packages/k/${package}.rpm
-      dnf install -y ./${package}.rpm
+      set -e
+      dnf -y install https://dl.rockylinux.org/vault/rocky/#{node['platform_version']}/BaseOS/#{node['kernel']['machine']}/os/Packages/k/${package}.rpm
     fi
     dnf clean all
     INSTALL_KERNEL_SOURCE
   end unless on_docker?
 end
 
+def kernel_source_package_version
+  node['kernel']['release']
+end
+
 def default_packages
   # environment-modules required by EFA, Intel MPI and ARM PL
   # iptables needed for IMDS setup