CI: stop verifying kernel subpackage names (!907)

At the moment we check that the kernel variants for a device package
match the suffix of an existing linux-postmarketos-<suffix> package.

However, in most cases the name of the kernel subpackage has nothing
to do with the actual kernel that is used:

  - the kernel subpackages usually have generic names like "mainline" or
    "downstream", which have nothing to do with the actual suffixes like
    "qcom-msm8916", "allwinner" or "novathor"

  - pine64-dontbeevil uses kernel subpackages to switch between
    "longts" and "shortts" device tree variants. Both are actually
    using linux-postmarketos-allwinner.

So far we have been whitelisting names like "longts" or "shortts",
but the check does not seem very useful overall.

Removing it fixes the following CI failure for MSM8916:
  RuntimeError: Invalid kernel subpackage name 'mainline-modem',
  valid: ['downstream', 'rpi', 'rpi2', 'longts', 'shortts', 'stable', 'mainline',
          'allwinner', 'qcom-msm8916', 'qcom-msm8974', 'novathor']

.gitlab-ci/testcases/test_aports.py

@@ -127,13 +127,7 @@ def test_aports_device_kernel(args):
     Verify the kernels specified in the device packages:
     * Kernel must not be in depends when kernels are in subpackages
     * Check if only one kernel is defined in depends
-    * Validate kernel subpackage names
     """
-    # Generate list of valid subpackages
-    valid_subpackages = ["downstream", "rpi", "rpi2", "longts", "shortts"]
-    for path in glob.glob(args.aports + "/main/linux-postmarketos-*"):
-        suffix = os.path.basename(path)[len("linux-postmarketos-"):]
-        valid_subpackages.append(suffix)
 
     # Iterate over device aports
     for path in glob.glob(args.aports + "/device/device-*/APKBUILD"):
@@ -166,11 +160,3 @@ def test_aports_device_kernel(args):
                                " multiple kernels in depends (see"
                                " <https://postmarketos.org/devicepkg>): " +
                                path)
-
-        # Verify subpackages
-        if kernels_subpackages:
-            for subpackage in kernels_subpackages:
-                if subpackage not in valid_subpackages:
-                    raise RuntimeError("Invalid kernel subpackage name '" +
-                                       subpackage + "', valid: " +
-                                       str(valid_subpackages))