config: Add default client arch defines for intel architectures

Define default PXE client architecture identifiers for IA32 (0x0 aka
Intel x86PC) and Intel x86-64 (0x9 aka EFI x86-64).

This prepares for usage for config_distro_defaults in the sandbox
architecture
Signed-off-by: NSjoerd Simons <sjoerd.simons@collabora.co.uk>

include/config_distro_defaults.h

@@ -29,6 +29,10 @@
 #else
 #define CONFIG_BOOTP_VCI_STRING         "U-boot.arm"
 #endif
+#elif defined(__i386__)
+#define CONFIG_BOOTP_PXE_CLIENTARCH     0x0
+#elif defined(__x86_64__)
+#define CONFIG_BOOTP_PXE_CLIENTARCH     0x9
 #endif
 
 #define CONFIG_OF_LIBFDT