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/Kconfig b/common/spl/Kconfig
index 4a739a7..e0d0a6f 100644
--- a/common/spl/Kconfig
+++ b/common/spl/Kconfig
@@ -919,6 +919,22 @@
 
 endif # SPL_OS_BOOT
 
+config SPL_FALCON_BOOT_MMCSD
+	bool "Enable Falcon boot from MMC or SD media"
+	depends on SPL_OS_BOOT && SPL_MMC
+	help
+	  Select this if the Falcon mode OS image mode is on MMC or SD media.
+
+config SYS_MMCSD_RAW_MODE_KERNEL_SECTOR
+	hex "Falcon mode: Sector to load kernel uImage from MMC"
+	depends on SPL_FALCON_BOOT_MMCSD
+	help
+	  When Falcon mode is used with an MMC or SD media, SPL needs to know
+	  where to look for the kernel uImage. The image is expected to begin
+	  at the raw MMC specified in this config.
+	  Note that the Falcon mode image can also be a FIT, if FIT support is
+	  enabled.
+
 config SPL_PAYLOAD
 	string "SPL payload"
 	default "tpl/u-boot-with-tpl.bin" if TPL