flounder: Node group should be drmrpc

(cherry pick from commit afbae105487ffb4c64c8e67c620f92dc88a51465)

Allow mediaDrmServer which is a seperate process access to
Tegra AVP channel for video decode.

Bug: 26780693
Change-Id: I810572c0ba58e6aeb29eb2464e659a4ade7aa68a
1 file changed