firmware: qcom_scm: drop redandant of_platform_populate

Now that of_platform_default_populate_init() takes care of populating
all the devices under the /firmware/ node, this patch removes the
redandant call to of_platform_populate here.

Cc: Andy Gross <andy.gross@linaro.org>
Cc: David Brown <david.brown@linaro.org>
Cc: linux-arm-msm@vger.kernel.org
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Andy Gross <andy.gross@linaro.org>