Make a media type deps public to make includes allowed

Since mojo will insert
#include "media/base/ipc/media_param_traits_macros.h"
in code using the media types mojo types, the dependency
on media/base/ipc, where that header lives, need to be
public.

The error reported otherwise (by gn check --check-generated) was:

ERROR at //out/Default/gen/media/mojo/interfaces/traits_test_service.mojom-test-utils.cc:30:11: Can't include this header from here.
#include "media/base/ipc/media_param_traits_macros.h"
          ^-----------------------------------------
The target:
  //media/mojo/interfaces:test_interfaces
is including a file from the target:
  //media/base/ipc:ipc

It's usually best to depend directly on the destination target.
In some cases, the destination target is considered a subcomponent
of an intermediate target. In this case, the intermediate target
should depend publicly on the destination to forward the ability
to include headers.

Dependency chain (there may also be others):
  //media/mojo/interfaces:test_interfaces -->
  //media/mojo/interfaces:interfaces --[private]-->
  //media/base/ipc:ipc

Bug: 938893
Change-Id: I7781ced5305ace65654da9ee4cf1a7f82ecac1a5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1538434
Commit-Queue: Daniel Cheng <dcheng@chromium.org>
Auto-Submit: Daniel Bratell <bratell@opera.com>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#644368}

media/mojo/interfaces/media_types.typemap

@@ -31,9 +31,6 @@ traits_headers = [ "//media/base/ipc/media_param_traits_macros.h" ]
 
 public_deps = [
   "//media",
-]
-
-deps = [
   "//media/base/ipc",
 ]