soc/apollolake: Add early serial driver for BOOTBLOCK_CONSOLE

Early UART driver is for bootblock and romstage. It is supposed to be used
when BOOTBLOCK_CONSOLE is enabled. This also adds few configuration bits
in bootblock requiered for serial to be set up.

Change-Id: I15520d566f107797e68d618885d4379e73d0fa45
Signed-off-by: Andrey Petrov <andrey.petrov@intel.com>
Reviewed-on: https://review.coreboot.org/13677
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@chromium.org>

src/soc/intel/apollolake/Makefile.inc

@@ -9,14 +9,20 @@ subdirs-y += ../../../cpu/x86/tsc
 
 bootblock-y += bootblock/bootblock.c
 bootblock-y += bootblock/cache_as_ram.S
+bootblock-y += bootblock/bootblock.c
 bootblock-y += gpio.c
 bootblock-y += placeholders.c
+bootblock-y += tsc_freq.c
+bootblock-y += uart_early.c
 
 romstage-y += placeholders.c
 romstage-y += gpio.c
+romstage-y += uart_early.c
+
 smm-y += placeholders.c
 ramstage-y += placeholders.c
 ramstage-y += gpio.c
+ramstage-y += uart_early.c
 
 CPPFLAGS_common += -I$(src)/soc/intel/apollolake/include