firmware: qcom_scm: Fix the __qcom_scm_is_call_available

secure communication QCOM_IS_CALL_AVAIL_CMD function should be
using normal secure call instead of fast call. So fix the
 __qcom_scm_is_call_available() to use normal scm call
qcom_scm_call().

Change-Id: Ie8bb79d112e02f66383e1eb561bc78accdce9b4f
Signed-off-by: Prasad Sodagudi <psodagud@codeaurora.org>