qseecom: add additonal reentrancy check before scm call

scm call of send data will fail with EBUSY if there are more than one
TAs requesting listener services, add additional checks before scm call
and wait until no more than one listener request in the system.

Change-Id: Ic891e687062dc52f02639605f3bac0e1c4540a6f
Signed-off-by: Zhen Kong <zkong@codeaurora.org>