x86: Add new slimbootloader CPU type

This slimbootloader CPU type is to enable U-Boot as a payload which
runs on top of Slim Bootloader (https://github.com/slimbootloader).
The Slim Bootloader is designed with multi-stage architecture for
the execution from reset vector to OS booting, and supports QEMU,
Apollolake, Whiskeylake and Coffeelake platforms consuming Intel
FSP (https://github.com/IntelFsp) for silicon initialization
including CAR and memory initialization.
The Slim Bootloader generates new HOB (Hand Off Block) which are
serial port info, memory map info, performance data info and so on,
and passes it to a Payload. U-Boot as a payload will use these HOB
information for basic initialization such as serial console.

As an initial commit,
- Add CONFIG_SYS_SLIMBOOTLOADER to enable slimbootloader CPU type
- Add new arch/x86/cpu/slimbootloader directory with minimum codes
- Get hob_list pointer from Slim Bootloader

Signed-off-by: Aiden Park <aiden.park@intel.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Tested-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/arch/x86/cpu/start.S b/arch/x86/cpu/start.S
index 4a82add..71cd70f 100644
--- a/arch/x86/cpu/start.S
+++ b/arch/x86/cpu/start.S
@@ -97,7 +97,7 @@
 	jmp	car_init
 .globl car_init_ret
 car_init_ret:
-#ifndef CONFIG_HAVE_FSP
+#ifndef CONFIG_USE_HOB
 	/*
 	 * We now have CONFIG_SYS_CAR_SIZE bytes of Cache-As-RAM (or SRAM,
 	 * or fully initialised SDRAM - we really don't care which)
@@ -137,12 +137,13 @@
 
 	/* Get address of global_data */
 	mov	%fs:0, %edx
-#ifdef CONFIG_HAVE_FSP
+#ifdef CONFIG_USE_HOB
 	/* Store the HOB list if we have one */
 	test	%esi, %esi
 	jz	skip_hob
 	movl	%esi, GD_HOB_LIST(%edx)
 
+#ifdef CONFIG_HAVE_FSP
 	/*
 	 * After fsp_init() returns, the stack has already been switched to a
 	 * place within system memory as defined by CONFIG_FSP_TEMP_RAM_ADDR.
@@ -151,6 +152,7 @@
 	 */
 	subl	$CONFIG_FSP_SYS_MALLOC_F_LEN, %esp
 	movl	%esp, GD_MALLOC_BASE(%edx)
+#endif
 skip_hob:
 #else
 	/* Store table pointer */