docs/kernel-parameters: Update descriptions for "mitigations=" param with retbleed

commit ea304a8b89fd0d6cf94ee30cb139dc23d9f1a62f upstream. Updates descriptions for "mitigations=off" and "mitigations=auto,nosmt" with the respective retbleed= settings. Signed-off-by: Eiichi Tsukata <eiichi.tsukata@nutanix.com> Signed-off-by: Borislav Petkov <bp@suse.de> Cc: corbet@lwn.net Link: https://lore.kernel.org/r/20220728043907.165688-1-eiichi.tsukata@nutanix.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: Etsukata

Documentation/admin-guide/kernel-parameters.txt

@@ -3020,6 +3020,7 @@
  no_entry_flush [PPC]
  no_uaccess_flush [PPC]
  mmio_stale_data=off [X86]
+ retbleed=off [X86]
 
 Exceptions:
  This does not have any effect on
@@ -3042,6 +3043,7 @@
  mds=full,nosmt [X86]
  tsx_async_abort=full,nosmt [X86]
  mmio_stale_data=full,nosmt [X86]
+ retbleed=auto,nosmt [X86]
 
 mminit_loglevel=
 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this