soc/intel/bdw: Remove spurious comment

Change-Id: I45f2ca809a6acfcb80a742d29c045d04888e4d7f
Signed-off-by: Nico Huber <nico.h@gmx.de>
Reviewed-on: https://review.coreboot.org/c/31321
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>

src/soc/intel/broadwell/bootblock/cpu.c

@@ -41,7 +41,6 @@ static void enable_rom_caching(void)
 	msr_t msr;
 
 	disable_cache();
-	/* Why only top 4MiB ? */
 	set_var_mtrr(1, CACHE_ROM_BASE, CACHE_ROM_SIZE, MTRR_TYPE_WRPROT);
 	enable_cache();