ARM: SAMSUNG: Fix build without SDHCI controllers for S3C64XX

This patch fixes the following compilation problem if only NCP machine
is selected:

arch/arm/mach-s3c64xx/s3c6410.c: In function 's3c6410_map_io':
arch/arm/mach-s3c64xx/s3c6410.c:51: error: implicit declaration of function 's3c6410_default_sdhci2'

And also adds missed 's3c6400_default_sdhci2'.
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
[kgene.kim@samsung.com: minor title fix and added comments]
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>

arch/arm/plat-samsung/include/plat/sdhci.h

@@ -166,8 +166,10 @@ static inline void s3c6410_default_sdhci2(void) { }
 #else
 static inline void s3c6410_default_sdhci0(void) { }
 static inline void s3c6410_default_sdhci1(void) { }
+static inline void s3c6410_default_sdhci2(void) { }
 static inline void s3c6400_default_sdhci0(void) { }
 static inline void s3c6400_default_sdhci1(void) { }
+static inline void s3c6400_default_sdhci2(void) { }
 
 #endif /* CONFIG_S3C64XX_SETUP_SDHCI */