wil6210: new SW reset

New firmware allows for shorter SW reset procedure.
After SW reset, FW raises "fw done" IRQ, at this
moment mailbox control structures are initialized, driver caches it.

New status bit wil_status_reset_done introduced to track completion
of the reset. It is set by "fw ready" irq, and required for WMI rx flow
to access control structures.

WMI Tx flow protected by other status bit, wil_status_fwready. It can't
be set before wil_status_reset_done is set by design.

Signed-off-by: Vladimir Kondratiev <qca_vkondrat@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>