[mask_rom] Remove out of date comment

Signed-off-by: Michael Munday <mike.munday@lowrisc.org>
diff --git a/sw/device/silicon_creator/mask_rom/mask_rom_start.S b/sw/device/silicon_creator/mask_rom/mask_rom_start.S
index df220f2..1da2fb0 100644
--- a/sw/device/silicon_creator/mask_rom/mask_rom_start.S
+++ b/sw/device/silicon_creator/mask_rom/mask_rom_start.S
@@ -248,9 +248,6 @@
   call crt_section_copy
 
   // Initialize the `.bss` section.
-  //
-  // We do this despite zeroing all of SRAM above, so that we still zero `.bss`
-  // once we've enabled SRAM scrambling.
   la   a0, _bss_start
   la   a1, _bss_end
   call crt_section_clear