arm/dt: mpq8092: add compatible string for simulator

Add compatiable string("qcom,sim") for 8092 simulator.
Without this, the secondary cpu boot sequence will take
the path of actual silicon instead of simulator.

Change-Id: Ia17cabba4de757507397345d6c9d5536cbcca4bc
Signed-off-by: Srinivas Ramana <sramana@codeaurora.org>