For all unrecoverable errors we are missing to log the
error, Since machine_check_log_err() is not getting called
for unrecoverable errors. machine_check_log_err() is called
from deferred handler, To run deferred handlers we have to do
irq work raise from the exception handler.

For recoverable errors exception vector code takes care of
running deferred handlers.

For unrecoverable errors raise irq work in save_mce_event(),
So that we log the error from MCE deferred handler.

Log without this change

 MCE: CPU27: machine check (Severe)  Real address Load/Store (foreign/control memory) [Not recovered]
 MCE: CPU27: PID: 10580 Comm: inject-ra-err NIP: [0000000010000df4]
 MCE: CPU27: Initiator CPU
 MCE: CPU27: Unknown

Log with this change

 MCE: CPU24: machine check (Severe)  Real address Load/Store (foreign/control memory) [Not recovered]
 MCE: CPU24: PID: 1589811 Comm: inject-ra-err NIP: [0000000010000e48]
 MCE: CPU24: Initiator CPU
 MCE: CPU24: Unknown
 RTAS: event: 5, Type: Platform Error (224), Severity: 3
Signed-off-by: Ganesh Goudar <ganeshgr@linux.ibm.com>
Reviewed-by: Mahesh Salgaonkar <mahesh@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20230201095933.129482-1-ganeshgr@linux.ibm.com