am43xx_evm: qspi: do not define DM_SPI and DM_SPI_FLASH for spl

Since OMAP's spl doesn't support DM currently, do not define
DM_SPI and DM_SPI_FLASH for spl build.

Signed-off-by: Mugunthan V N <mugunthanvnm@ti.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Jagan Teki <jteki@openedev.com>

include/configs/am43xx_evm.h

@@ -142,6 +142,8 @@
  */
 #ifdef CONFIG_SPL_BUILD
 #undef CONFIG_DM_MMC
+#undef CONFIG_DM_SPI
+#undef CONFIG_DM_SPI_FLASH
 #endif
 
 #ifndef CONFIG_SPL_BUILD