ci: Split platform matrix in zephyr.yml workflow

Separates platform entries in the configuration array to
reduce reduce the number of platfroms run per runner as
we are approaching size limits from building too many at a time.

Signed-off-by: Christopher Turner <christopher.g.turner@intel.com>

Author: cgturner1

.github/workflows/zephyr.yml

@@ -116,13 +116,16 @@ jobs:
         # many lines. Pay attention to COMMAS.
         IPC_platforms: [
           # - IPC3 default
-          imx8 imx8x imx8m imx8ulp,
+          imx8 imx8x,
+          imx8m imx8ulp,
           # - IPC4 default, released
-          mtl lnl,
+          mtl,
+          lnl,
           # active development
           ptl,
           # Temporary testbed for Zephyr development.
-          tgl tgl-h,
+          tgl,
+          tgl-h
         ]
         build_opts: [""]
         # Sparse matrices are complicated, you must read this page slowly:
@@ -462,7 +465,8 @@ jobs:
           for regdir in 'linux-build *-d *.*' \
                         'linux-build *.*lnl.*' \
                         'windows-build *.*mtl.*' \
-                        'windows-build *tgl tgl-h'; do
+                        'windows-build *tgl-h ' \
+                        'windows-build *tgl'; do
             find . -maxdepth 1 | grep -q "\./${regdir}\$" ||
               { >&2 printf 'Missing %s\n' "${regdir}"; exit 1; }
           done