arm64: ssbd: Drop #ifdefs for PR_SPEC_STORE_BYPASS

Now that we're all merged nicely into mainline, there's no need to check
to see if PR_SPEC_STORE_BYPASS is defined.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

arch/arm64/kernel/ssbd.c

@@ -11,9 +11,7 @@
 
 /*
  * prctl interface for SSBD
- * FIXME: Drop the below ifdefery once merged in 4.18.
  */
-#ifdef PR_SPEC_STORE_BYPASS
 static int ssbd_prctl_set(struct task_struct *task, unsigned long ctrl)
 {
 	int state = arm64_get_ssbd_state();
@@ -107,4 +105,3 @@ int arch_prctl_spec_ctrl_get(struct task_struct *task, unsigned long which)
 		return -ENODEV;
 	}
 }
-#endif	/* PR_SPEC_STORE_BYPASS */