powerpc/64s: Remove old STAB comment

This used to be about the 0x4300 handler, but that was moved in commit
da2bc464 ("powerpc/64s: Add new exception vector macros").

Note that "STAB" here refers to "Segment Table" not the debug format.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220928130912.1732466-1-mpe@ellerman.id.au

arch/powerpc/kernel/exceptions-64s.S

@@ -3080,12 +3080,6 @@ MASKED_INTERRUPT hsrr=1
 	 * to HV=1 from HV=0 is delivered via real mode handlers.
 	 */
 
-	/*
-	 * This uses the standard macro, since the original 0x300 vector
-	 * only has extra guff for STAB-based processors -- which never
-	 * come here.
-	 */
-
 USE_FIXED_SECTION(virt_trampolines)
 	/*
 	 * All code below __end_soft_masked is treated as soft-masked. If