ARM: dts: msm: Set slp_cmd_mode for power collapse on MDMcalifornium

Enable qcom,slp_cmd_mode only for rpm assisted power
collapse sequence.

Change-ID: I06e984301344d3831e3c57e2c60e2385b268712e
Signed-off-by: Girish S Ghongdemath <girishsg@codeaurora.org>