firmware: ti_sci: Add Initialization of dev_info head node

firmware: ti_sci: Add Initialization of dev_info head node

On K3 devices two drivers ti_sci and ti_sci_dm are supporting firmware
functions. At run time one of driver is used.

Driver ti_sci already initializing head for dev_list in its probe
function, but it was missed in ti_sci_dm driver.

So add head list init support for ti_sci_dm driver.
While at this, move init of list before usages in both functions.

Fixes: 5d5a699855a7("firmware: ti_sci: Add support for Resoure Management at R5 SPL stage")
Reviewed-by: Neha Malcom Francis <n-francis@ti.com>
Signed-off-by: Udit Kumar <u-kumar1@ti.com>
Reviewed-by: Nishanth Menon <nm@ti.com>