spl: Convert spl_nor_load_image() to use linker list

Add a linker list declaration for this method and remove the explicit
switch() code.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Tom Rini <trini@konsulko.com>
diff --git a/common/spl/spl.c b/common/spl/spl.c
index cef5ff9..978df64 100644
--- a/common/spl/spl.c
+++ b/common/spl/spl.c
@@ -384,10 +384,6 @@
 		return loader->load_image(&bootdev);
 
 	switch (boot_device) {
-#ifdef CONFIG_SPL_NOR_SUPPORT
-	case BOOT_DEVICE_NOR:
-		return spl_nor_load_image(&bootdev);
-#endif
 #ifdef CONFIG_SPL_YMODEM_SUPPORT
 	case BOOT_DEVICE_UART:
 		return spl_ymodem_load_image(&bootdev);
diff --git a/common/spl/spl_nor.c b/common/spl/spl_nor.c
index f10d679..b55fcc5 100644
--- a/common/spl/spl_nor.c
+++ b/common/spl/spl_nor.c
@@ -7,7 +7,7 @@
 #include <common.h>
 #include <spl.h>
 
-int spl_nor_load_image(struct spl_boot_device *bootdev)
+static int spl_nor_load_image(struct spl_boot_device *bootdev)
 {
 	int ret;
 	/*
@@ -70,3 +70,4 @@
 
 	return 0;
 }
+SPL_LOAD_IMAGE_METHOD(0, BOOT_DEVICE_NOR, spl_nor_load_image);