If the PM related modules are not loaded and PM firmware not configured,
the system suspend fails to resume. Let's fix this by adding initial
platform_suspend_ops to block suspend and warn about missing modules.

When pm33xx and wkup_m3_ipc have been loaded and m3 coprocessor booted
with it's firmware, pm33xx sets up working platform_suspend_ops. Note
that we need to configure at least PM_SUSPEND_STANDBY to have
suspend_set_ops().

Cc: Dave Gerlach <d-gerlach@ti.com>
Cc: Suman Anna <s-anna@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>