emualtor: cleanup media configuration

The media configuration is handled by goldfish/vendor.mk
already; clean them up from device.mk files.

this cl does not impact arm devices;
and it does the right thing for x86/64 devices
because the media configuration should go to vendor
instead of staying on system

BUG: 110030159
Change-Id: If492f1e01f600b1c969e9ef04598f7af6783970e