x86: Add a common HOB library

FSP (CONFIG_HAVE_FSP) and Slim Bootloader (CONFIG_SYS_SLIMBOOTLOADER)
consume HOB (CONFIG_USE_HOB) data from the each HOB list pointer.
Add a common HOB library in lib/hob.c and include/asm/hob.h.

Signed-off-by: Aiden Park <aiden.park@intel.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Tested-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/arch/x86/lib/Makefile b/arch/x86/lib/Makefile
index 436252d..906be5e 100644
--- a/arch/x86/lib/Makefile
+++ b/arch/x86/lib/Makefile
@@ -42,6 +42,7 @@
 ifndef CONFIG_SPL_BUILD
 obj-$(CONFIG_CMD_ZBOOT)	+= zimage.o
 endif
+obj-$(CONFIG_USE_HOB) += hob.o
 obj-$(CONFIG_HAVE_FSP) += fsp/
 
 ifdef CONFIG_SPL_BUILD