powerpc: mpc85xx: Fix check for CONFIG_SDCARD

Commit d433c74eecdc ("Convert CONFIG_SDCARD et al to Kconfig") converted
SYS_EXTRA_OPTIONS=SDCARD or SPIFLASH to config options CONFIG_SDCARD and
CONFIG_SPIFLASH, but left one occurance unchanged.

Fix this.

Fixes: d433c74eecdc ("Convert CONFIG_SDCARD et al to Kconfig")
Signed-off-by: Marek Behún <kabel@kernel.org>
Reviewed-by: Pali Rohár <pali@kernel.org>
diff --git a/arch/powerpc/cpu/mpc85xx/Kconfig b/arch/powerpc/cpu/mpc85xx/Kconfig
index 085ddd8..27f069a 100644
--- a/arch/powerpc/cpu/mpc85xx/Kconfig
+++ b/arch/powerpc/cpu/mpc85xx/Kconfig
@@ -15,7 +15,7 @@
 config FSL_PREPBL_ESDHC_BOOT_SECTOR
 	bool "Generate QorIQ pre-PBL eSDHC boot sector"
 	depends on MPC85xx
-	depends on SYS_EXTRA_OPTIONS = SDCARD
+	depends on SDCARD
 	help
 	  With this option final image would have prepended QorIQ pre-PBL eSDHC
 	  boot sector suitable for SD card images. This boot sector instruct