Fix mips emulator boot

The following commit introduced regression:
    7b5e1aba emulator: squash misc modifications from oc-emu-dev

Emulators for mips should also use unencrypted data partition like arm.
Encryption is only enabled for Intel.

Change-Id: I3dba08621d8f679a707f516fff735bba31bfc629
Signed-off-by: Miodrag Dinic <miodrag.dinic@imgtec.com>