qseecom: improve secure app session management

Make several changes to improve secure app session management.
First, app tied to the handle being closed (when qseecom_release
is invoked), is unloaded.

Second, we add support to handle multiple app load & unload. Media
server is associated with multiple apps on TZ-side. Unloading a single
app for clean up is not enough. QSEECOM needs to handle the app load
& unload of multiple apps associated with the client. During app_load
& app_unload along with app_id, app_name should also be checked.
Besides, keymaster will not be unloaded and app search execution during
app unloading is optimized.

Third, keymaster app has two names with different length: "keymaster" and
"keymaste". To compare the app names correctly, the shorter name length
is choosen for memcmp in __qseecom_send_cmd.

Change-Id: Ifd8f4508cd930630e8730f6699d66bf8668bbef6
Signed-off-by: Zhen Kong <zkong@codeaurora.org>