Use select() for gfxstream mesa3d_platforms flag

Minor cleanup, as it's now supported for srcs since b/358377461

Bug: 326956485
Test: m
Change-Id: I4dad7fb4debc30e1cd95cfacaac95a8f53ed539e
diff --git a/Android.bp b/Android.bp
index 4f17387..197c4a7 100644
--- a/Android.bp
+++ b/Android.bp
@@ -100,17 +100,6 @@
     ],
 }
 
-soong_config_module_type {
-    name: "gfxstream_cc_defaults_config_for_platform",
-    module_type: "cc_defaults",
-    config_namespace: "gfxstream",
-    variables: ["mesa3d_platforms"],
-    properties: [
-        "cflags",
-        "target.android.srcs",
-    ],
-}
-
 soong_config_string_variable {
     name: "mesa3d_platforms",
     values: [
@@ -120,34 +109,23 @@
     ],
 }
 
-gfxstream_cc_defaults_config_for_platform {
-    name: "gfxstream_guest_cc_defaults_for_platform",
-    soong_config_variables: {
-        mesa3d_platforms: {
-            // Android surfaceless build
-            none: {
-                cflags: [
-                    "-UANDROID",
-                    "-U__ANDROID__",
-                    "-DLINUX_GUEST_BUILD",
-                ],
-            },
-            // The default when variable is not set is Android
-            conditions_default: {
-                cflags: [
-                    "-DVK_USE_PLATFORM_ANDROID_KHR",
-                ],
-            },
-        },
-    },
-}
-
 cc_defaults {
     name: "gfxstream_guest_cc_defaults",
     defaults: [
         "gfxstream_cc_defaults",
-        "gfxstream_guest_cc_defaults_for_platform",
     ],
+    cflags: select(soong_config_variable("gfxstream", "mesa3d_platforms"), {
+        // Android surfaceless build
+        "none": [
+            "-UANDROID",
+            "-U__ANDROID__",
+            "-DLINUX_GUEST_BUILD",
+        ],
+        // The default when variable is not set is Android
+        default: [
+            "-DVK_USE_PLATFORM_ANDROID_KHR",
+        ],
+    }),
 }
 
 cc_defaults {