ibmvnic: Ensure login failure recovery is safe from other resets

ibmvnic: Ensure login failure recovery is safe from other resets

If a login request fails, the recovery process should be protected
against parallel resets. It is a known issue that freeing and
registering CRQ's in quick succession can result in a failover CRQ from
the VIOS. Processing a failover during login recovery is dangerous for
two reasons:
 1. This will result in two parallel initialization processes, this can
 cause serious issues during login.
 2. It is possible that the failover CRQ is received but never executed.
 We get notified of a pending failover through a transport event CRQ.
 The reset is not performed until a INIT CRQ request is received.
 Previously, if CRQ init fails during login recovery, then the ibmvnic
 irq is freed and the login process returned error. If failover_pending
 is true (a transport event was received), then the ibmvnic device
 would never be able to process the reset since it cannot receive the
 CRQ_INIT request due to the irq being freed. This leaved the device
 in a inoperable state.

Therefore, the login failure recovery process must be hardened against
these possible issues. Possible failovers (due to quick CRQ free and
init) must be avoided and any issues during re-initialization should be
dealt with instead of being propagated up the stack. This logic is
similar to that of ibmvnic_probe().

Fixes: dff515a3e71d ("ibmvnic: Harden device login requests")
Signed-off-by: Nick Child <nnac123@linux.ibm.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://lore.kernel.org/r/20230809221038.51296-5-nnac123@linux.ibm.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>