cpu/intel/haswell: Link tsc_freq.c in the bootblock

This provides tsc_freq_mhz implementation.

Change-Id: Ic6a84336f89a37aa412a9cc8c375fbd41dc09cf2
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/33176
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: HAOUAS Elyes <ehaouas@noos.fr>

src/cpu/intel/haswell/Makefile.inc

@@ -25,6 +25,7 @@ bootblock-y += ../car/non-evict/cache_as_ram.S
 bootblock-y += ../car/bootblock.c
 bootblock-y += ../../x86/early_reset.S
 bootblock-y += bootblock.c
+bootblock-y += tsc_freq.c
 
 postcar-y += ../car/non-evict/exit_car.S