qseecom: improve input sanitization in compat_qseecom

Make a change to sanitize userspace input data in compat_qseecom.c
and make sure it doesn't point to an arbitrary address.

Change-Id: I4cc32d9f0aa0d4807aa3546ff9ffd3ccc6dee2c9
Signed-off-by: Zhen Kong <zkong@codeaurora.org>