ANDROID: Kleaf: drop comments referring to android-mainline

Branches happen and the comments become stale.

Bug: 393366754
Change-Id: I6bbd74752bd2154d6560e0dd12dc169a5df611e2
Signed-off-by: Giuliano Procida <gprocida@google.com>

BUILD.bazel

@@ -110,7 +110,6 @@ write_file(
     ],
 )
 
-# Not enforced in android-mainline.
 common_kernel_protected_module_names(
     name = "gki_aarch64_protected_module_names",
     out = "gki/aarch64/protected_module_names",
@@ -128,7 +127,6 @@ write_file(
     ],
 )
 
-# Not enforced in android-mainline.
 common_kernel_protected_module_names(
     name = "gki_x86_64_protected_module_names",
     out = "gki/x86_64/protected_module_names",