lib/tpm2_session.c: Update tpm2_session_close
lib/tpm2_session.c: Update tpm2_session_close

1. Declare/ define variables closes to their scope of use
2. Set rc to tool_rc_general error explicitly on error paths
3. Do not use temporary return from function calls directly
   as function arguments.

Signed-off-by: Imran Desai <d01faadd01d89088a38277c634ffb396f2b368f8@intel.com>

01org/tpm2.0-tools,01org/tpm2.0-tools,01org/tpm2.0-tools