mmc: size optimization when !CONFIG_MMC_SPI

When CONFIG_MMC_SPI is not enabled, the MMC_MODE_SPI capability can
never be set. However there is code in mmc.c which uses the
mmc_host_is_spi macro to check that capability & act accordingly. If we
expand that macro to 0 when CONFIG_MMC_SPI is not set (since it will
always be 0 at runtime anyway) then the compiler can optimize away the
SPI-specific code paths in mmc.c.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>

include/mmc.h

@@ -335,7 +335,11 @@ int mmc_start_init(struct mmc *mmc);
 void mmc_set_preinit(struct mmc *mmc, int preinit);
 
 #ifdef CONFIG_GENERIC_MMC
+#ifdef CONFIG_MMC_SPI
 #define mmc_host_is_spi(mmc)	((mmc)->host_caps & MMC_MODE_SPI)
+#else
+#define mmc_host_is_spi(mmc)	0
+#endif
 struct mmc *mmc_spi_init(uint bus, uint cs, uint speed, uint mode);
 #else
 int mmc_legacy_init(int verbose);