x86: sysreset: Allow reset driver to be included in SPL/TPL

At present this driver is always included in SPL and TPL, if U-Boot proper
enables it. Update the Makefile to provide full control using the existing
Kconfig options.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
[bmeng: make the Kconfig help text a little bit clearer]
Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/drivers/sysreset/Kconfig b/drivers/sysreset/Kconfig
index f565ae0..5e6293a 100644
--- a/drivers/sysreset/Kconfig
+++ b/drivers/sysreset/Kconfig
@@ -107,6 +107,18 @@
 	help
 	  Reboot support for generic x86 processor reset.
 
+config SYSRESET_SPL_X86
+	bool "Enable support for x86 processor reboot driver in SPL"
+	depends on X86
+	help
+	  Reboot support for generic x86 processor reset in SPL.
+
+config SYSRESET_TPL_X86
+	bool "Enable support for x86 processor reboot driver in TPL"
+	depends on X86
+	help
+	  Reboot support for generic x86 processor reset in TPL.
+
 config SYSRESET_MCP83XX
 	bool "Enable support MPC83xx SoC family reboot driver"
 	help