sunxi: Turn MMC_SUNXI_SLOT_EXTRA into a proper Kconfig option

Note we also drop the SPL check for initializing the 2nd mmc slot, the SPL
check is not necessary with Kconfig, because only options explicitly marked
as also being for the SPL get set during SPL builds.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Ian Campbell <ijc@hellion.org.uk>

board/sunxi/Kconfig

@@ -67,4 +67,12 @@ config MMC3_CD_PIN
 	---help---
 	See MMC0_CD_PIN help text.
 
+config MMC_SUNXI_SLOT_EXTRA
+	int "mmc extra slot number"
+	default -1
+	---help---
+	sunxi builds always enable mmc0, some boards also have a second sdcard
+	slot or emmc on mmc1 - mmc3. Setting this to 1, 2 or 3 will enable
+	support for this.
+
 endif

board/sunxi/board.c

@@ -106,7 +106,7 @@ int board_mmc_init(bd_t *bis)
 {
 	mmc_pinmux_setup(CONFIG_MMC_SUNXI_SLOT);
 	sunxi_mmc_init(CONFIG_MMC_SUNXI_SLOT);
-#if !defined (CONFIG_SPL_BUILD) && defined (CONFIG_MMC_SUNXI_SLOT_EXTRA)
+#if CONFIG_MMC_SUNXI_SLOT_EXTRA != -1
 	mmc_pinmux_setup(CONFIG_MMC_SUNXI_SLOT_EXTRA);
 	sunxi_mmc_init(CONFIG_MMC_SUNXI_SLOT_EXTRA);
 #endif