soc/intel/{broadwell,skylake}: Remove unused SERIAL_CPU_INIT

Change-Id: I2296ab3c53a82ee990649e35e1370e1dd304e392
Signed-off-by: Elyes HAOUAS <ehaouas@noos.fr>
Reviewed-on: https://review.coreboot.org/29600
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>

src/soc/intel/broadwell/Kconfig

@@ -80,10 +80,6 @@ config MMCONF_BASE_ADDRESS
 	hex
 	default 0xf0000000
 
-config SERIAL_CPU_INIT
-	bool
-	default n
-
 config SMM_TSEG_SIZE
 	hex
 	default 0x800000

src/soc/intel/skylake/Kconfig

@@ -168,10 +168,6 @@ config PCR_BASE_ADDRESS
 	help
 	  This option allows you to select MMIO Base Address of sideband bus.
 
-config SERIAL_CPU_INIT
-	bool
-	default n
-
 config SERIRQ_CONTINUOUS_MODE
 	bool
 	default n