arm/dt: msm8610: Enable SPM only when we enter low power mode

On some hardware if the core is held in reset SPM state machine
starts execution. As a result, enabling SPM before programming the
SPM sequence could result in SPM executing its low power mode state
machine while the core is still held in reset. Disable SPM by
default as it gets enabled when we enter low power mode.

Change-Id: I34393ded3721503da1382492d1894424367d5e3e
Signed-off-by: Priyanka Mathur <pmathur@codeaurora.org>