Add LICENSE to the "license_text" property of external_libdrm_license module. am: 73c5f61f6f am: f44d408572

Original change: https://android-review.googlesource.com/c/platform/external/libdrm/+/3096310

Change-Id: Ica4857b34035d354e3379117e3d1af58a5816626
Signed-off-by: Automerger Merge Worker <[email protected]>