Correct return codes in documentation

Some of the AMediaDrm APIs mentioned a non-existant error code
may be returned in the comments. This gets reflected in the
public documentation at https://developer.android.com/ndk/reference/group/

MEDIADRM_OK -> AMEDIA_OK
MEDIADRM_SHORT_BUFFER -> AMEDIA_DRM_SHORT_BUFFER
MEDIADRM_NOT_PROVISIONED_ERROR -> AMEDIA_DRM_NOT_PROVISIONED
MEDIADRM_DEVICE_REVOKED_ERROR -> AMEDIA_DRM_DEVICE_REVOKED
MEDIADRM_RESOURCE_BUSY_ERROR -> AMEDIA_DRM_RESOURCE_BUSY

Bug: 257289554
Change-Id: I3bac8115969372dd3ff392ef09f4c6c10698fe4a
Test: Compile frameworks/av