bnxt_en: Manage the FW trace context memory

bnxt_en: Manage the FW trace context memory

The FW trace memory pages will be added to the ethtool -w coredump
in later patches.  In addition to the raw data, the driver has to
add a header to provide the head and tail information on each FW
trace log segment when creating the coredump.  The FW sends an async
message to the driver after DMAing a chunk of logs to the context
memory to indicate the last offset containing the tail of the logs.
The driver needs to keep track of that.

Reviewed-by: Hongguang Gao <[email protected]>
Signed-off-by: Shruti Parab <[email protected]>
Signed-off-by: Michael Chan <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>