x86/bugs: inverted documentation of spectre_v2_heuristics=ssbd=off

The heuristic prevents the kernel from enabling IBRS because SSB is
being mitigated, not the other way around.

Orabug: 28362348
Fixes: 648702f ("x86/bugs/IBRS: Disable SSB (RDS) if IBRS is selected for spectre_v2.")
Signed-off-by: Daniel Jordan <[email protected]>
Reviewed-by: Alexandre Chartre <[email protected]>

Author: danieljordan10

Documentation/admin-guide/kernel-parameters.txt

@@ -4081,8 +4081,8 @@
 			skylake=off	- do not use IBRS if present on Skylake
 					  instead of retpoline (this is equivalant
 				          to spectre_v2=retpoline,generic).
-			ssbd=off         - do not activate the Speculative Store Bypass
-                                          mitigation if doing IBRS.
+			ssbd=off        - do not use IBRS if mitigating
+					  Speculative Store Bypass.
 
 	spia_io_base=	[HW,MTD]
 	spia_fio_base=