qcacmn: Send max commands as param to wmi_unified_attach

Modify arguments of wmi_unified_attach to use struct to
send attach params instead of individual params. Add max
WMI commands as a param. Based on requirement MAX WMI
commands value is different. In case of AP that supports
16 VAPs and more than 512 clients, 1024 commands is not
enough. Use this param to configure this value based on
the requirement.

Change-Id: I4e778475481e509051dfbac70980614b644e1b4a
CRs-fixed: 2034438
3 files changed