arm64: mm: remove reference to tlb.S from comment block

tlb.S has been removed since fa48e6f7 "arm64: mm: Optimise tlb flush logic
where we have >4K granule", so align comment with that.
Signed-off-by: NVladimir Murzin <vladimir.murzin@arm.com>
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>

arch/arm64/include/asm/tlbflush.h

@@ -28,8 +28,6 @@
  *	TLB Management
  *	==============
  *
- *	The arch/arm64/mm/tlb.S files implement these methods.
- *
  *	The TLB specific code is expected to perform whatever tests it needs
  *	to determine if it should invalidate the TLB for each call.  Start
  *	addresses are inclusive and end addresses are exclusive; it is safe to