spl: Move SPL_MMC_TINY option to appear under SPL menu

The SPL_MMC_TINY implements feature-reduced MMC support
on SPL, and as such, it's more consistent and convenient
to find it as part of the SPL configuration.

Signed-off-by: Ezequiel Garcia <ezequiel@collabora.com>
diff --git a/common/spl/Kconfig b/common/spl/Kconfig
index a48617d..126931b 100644
--- a/common/spl/Kconfig
+++ b/common/spl/Kconfig
@@ -572,6 +572,23 @@
 	  this option to build the drivers in drivers/mmc as part of an SPL
 	  build.
 
+config SPL_MMC_TINY
+	bool "Tiny MMC framework in SPL"
+	depends on SPL_MMC_SUPPORT
+	default n
+	help
+	  Enable MMC framework tinification support. This option is useful if
+	  if your SPL is extremely size constrained. Heed the warning, enable
+	  this option if and only if you know exactly what you are doing, if
+	  you are reading this help text, you most likely have no idea :-)
+
+	  The MMC framework is reduced to bare minimum to be useful. No malloc
+	  support is needed for the MMC framework operation with this option
+	  enabled. The framework supports exactly one MMC device and exactly
+	  one MMC driver. The MMC driver can be adjusted to avoid any malloc
+	  operations too, which can remove the need for malloc support in SPL
+	  and thus further reduce footprint.
+
 config SPL_MMC_WRITE
 	bool "MMC/SD/SDIO card support for write operations in SPL"
 	depends on SPL_MMC_SUPPORT