[efi] Enable "cpuid" command by default for EFI

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/config/defaults/efi.h

 #define	IMAGE_SCRIPT		/* iPXE script image support */
 
 #define	REBOOT_CMD		/* Reboot command */
+#define	CPUID_CMD		/* x86 CPU feature detection command */
 
 #endif /* CONFIG_DEFAULTS_EFI_H */