spl: Convert SYS_MMCSD_RAW_MODE_KERNEL_SECTOR to Kconfig

Falcon mode is very useful in improving boot speed. A question that
Falcon mode asks is "Where do I look for the kernel". With MMC boot
media, the correct answer is CONFIG_SYS_MMCSD_RAW_MODE_KERNEL_SECTOR.
The scope of this patch is to move this to Kconfig.

It is possible for a system to support Falcon mode from NOR but not
MMC. In that case, mmc_load_image_raw_os() would not be used. To
address this, conditionally compile mmc_load_image_raw_os() when
SPL_FALCON_BOOT_MMCSD, instead of SPL_OS_BOOT.

Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
[trini: Move spl_start_uboot to its own guard in spl_mmc.c, rerun migration]
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/common/spl/spl_mmc.c b/common/spl/spl_mmc.c
index d550da2..1c41d24 100644
--- a/common/spl/spl_mmc.c
+++ b/common/spl/spl_mmc.c
@@ -222,7 +222,7 @@
 }
 #endif
 
-#if CONFIG_IS_ENABLED(OS_BOOT)
+#if CONFIG_IS_ENABLED(FALCON_BOOT_MMCSD)
 static int mmc_load_image_raw_os(struct spl_image_info *spl_image,
 				 struct spl_boot_device *bootdev,
 				 struct mmc *mmc)
@@ -257,10 +257,6 @@
 	return 0;
 }
 #else
-int spl_start_uboot(void)
-{
-	return 1;
-}
 static int mmc_load_image_raw_os(struct spl_image_info *spl_image,
 				 struct spl_boot_device *bootdev,
 				 struct mmc *mmc)
@@ -269,6 +265,13 @@
 }
 #endif
 
+#ifndef CONFIG_SPL_OS_BOOT
+int spl_start_uboot(void)
+{
+	return 1;
+}
+#endif
+
 #ifdef CONFIG_SYS_MMCSD_FS_BOOT_PARTITION
 static int spl_mmc_do_fs_boot(struct spl_image_info *spl_image,
 			      struct spl_boot_device *bootdev,