preempt_rt: Fixups

- get rid of the deprecated _kver_subver_map and related check
- notify the user about the last known good kernel version target of the PREEMPT_RT patchset
- use warning instead of msg2 for PREEMPT_RT patch skipping since we are skipping a very impacting patch explicitly requested by the .cfg

linux-tkg-config/prepare

@@ -35,28 +35,6 @@ for _key in "${_current_kernels[@]}" "${_eol_kernels[@]}"; do
   _kver_latest_tags_map[$_key]=$(echo "$_kernel_tags" | grep -F "v$_key" | tail -1 | cut -c1-)
 done
 
-# only used by workflow trigger script
-typeset -Ag _kver_subver_map
-_kver_subver_map=(
-  ["5.4"]="214"
-  ["5.7"]="19"
-  ["5.8"]="18"
-  ["5.9"]="16"
-  ["5.10"]="144"
-  ["5.11"]="22"
-  ["5.12"]="19"
-  ["5.13"]="19"
-  ["5.14"]="21"
-  ["5.15"]="69"
-  ["5.16"]="20"
-  ["5.17"]="15"
-  ["5.18"]="19"
-  ["5.19"]="10"
-  ["6.0"]="rc6"
-)
-
-
-
 # PREEMPT_RT's supported kernel subversion
 typeset -Ag _rt_subver_map
 _rt_subver_map=(
@@ -654,7 +632,7 @@ _tkg_srcprep() {
     if [ ${_rt_subver_map[$_basekernel]+_} = "_" ]; then
       preempt_rt_ksubver="${_rt_subver_map[$_basekernel]}"
       # Check if subversion is supported, skip check if forced
-      if [ "${_preempt_rt_force}" = "1" ] || [ "${preempt_rt_ksubver}" = "${_kver_subver_map[$_basekernel]}" ]; then
+      if [ "${_preempt_rt_force}" = "1" ] || [ "${preempt_rt_ksubver}" = "${_sub}" ]; then
         preempt_rt_file_gz="patch-${_basekernel}.${preempt_rt_ksubver}-rt${_rt_rev_map["$_basekernel"]}.patch.gz"
         preempt_rt_file=`basename ${preempt_rt_file_gz} .gz`
         curl "https://cdn.kernel.org/pub/linux/kernel/projects/rt/${_basekernel}/${preempt_rt_file_gz}" > "$srcdir"/"${preempt_rt_file_gz}"
@@ -665,10 +643,10 @@ _tkg_srcprep() {
         tkgpatch="$srcdir/${preempt_rt_file}"
         _msg="Applying PREEMPT_RT patch" && _tkg_patcher
       else
-        msg2 "Skipping PREEMPT_RT patch for ${_basekernel}.${_sub}"
+        warning "Skipping PREEMPT_RT patch for ${_basekernel}.${_sub} (last known good ${_basekernel}.${preempt_rt_ksubver})"
       fi
     else
-      msg2 "Skipping PREEMPT_RT patch on unsupported kernel version"
+      warning "Skipping PREEMPT_RT patch on unsupported kernel version"
     fi
   fi