ice: add functions to get and set Tx queue context

ice: add functions to get and set Tx queue context

The live migration driver will need to save and restore the Tx queue
context state from the hardware registers. This state contains both static
fields which do not change during Tx traffic as well as dynamic fields
which may change during Tx traffic.

Unlike the Rx context, the Tx queue context is accessed indirectly from
GLCOMM_QTX_CNTX_CTL and GLCOMM_QTX_CNTX_DATA registers. These registers are
shared by multiple PFs on the same PCIe card. Multiple PFs cannot safely
access the registers simultaneously, and there is no hardware semaphore or
logic to control access. To handle this, introduce the txq_ctx_lock to the
ice_adapter structure. This is similar to the ptp_gltsyn_time_lock. All PFs
on the same adapter share this structure, and use it to serialize access to
the registers to prevent error.

Add a new functions to get and set the Tx queue context through the
GLCOMM_QTX_CNTX_CTL interface. The hardware context values are stored in
the registers using the same packed format as the Admin Queue buffer.

The hardware buffer is 40 bytes wide, as it contains an additional 18 bytes
of internal state not sent with the Admin Queue buffer. For this reason, a
separate typedef and packing function must be used. We can share the same
packed fields definitions because we never need to unpack the internal
state. This is preferred, as it ensures the internal state is zero'd when
writing into HW, and avoids issues with reading by u32 registers into a
buffer of 22 bytes in length. Thanks to the typedefs, misuse of the API
with the wrong size buffer can easily be caught at compile time.

Note reading this data from hardware is essential because the current Tx
queue context may be different from the context as initially programmed by
the driver during VF initialization. When migrating a VF we must ensure the
target VF has identical context as the source VF did.

Co-developed-by: Yahui Cao <yahui.cao@intel.com>
Signed-off-by: Yahui Cao <yahui.cao@intel.com>
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Reviewed-by: Madhu Chittim <madhu.chittim@intel.com>
Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>