Fix exception on MediaDrm invalid property access

Accessing an invalid MediaDrm property would result in
an IllegalStateException.  This change causes
IllegalArgumentException to be thrown instead, which
is more appropriate.

Test: android.media.cts.ClearKeySystemTest passes
  and it fails prior to this CL.

bug:68765217
Change-Id: I858575dc8fe643a88381da49b543c5cc0d266e02