If the device does not report support for the RSS indirection table,
ena_rss_init_default() destroys the RSS state and returns EOPNOTSUPP.
ena_rss_configure() treats EOPNOTSUPP as success and returns 0, and
ena_up_complete() sets ENA_FLAG_RSS_ACTIVE on any 0 return.
Reading dev.ena.N.rss.key at this point causes kernel panic.
Every current device reports the indirection table, so reaching this
needs a device that is broken or misreporting.
The SYSINIT removed by a6205766b300 called ena_rss_init_default()
directly, saw the EOPNOTSUPP and cleared the flag. Routing the decision
through ena_rss_configure(), which hides EOPNOTSUPP, lost that.
Move the flag set into ena_rss_configure(), which can see whether a
table exists, and clear it when tbl_log_size is 0. ena_rss_configure()
is now the only place that sets or clears the flag.
Fixes: a6205766b300 ("ena: Fix RSS not working after driver reload")
MFC after: 3 days
Sponsored by: Amazon, Inc.