sys_process: Fix sys_process_get_id, add error_code

[elad335]

• Due to signed checks and do-while behavior of sys_process_get_id ids processing (checking bufsize), negative and 0 values are treated as 1.
• sys_process_get_id and sys_process_get_id2 are not the same syscall handling code, infact they have a few different error checks and capabilities.

Testcase : https://github.com/elad335/myps3tests/tree/master/ppu_tests/sys_process_get_id