sf: Move SPI flash drivers to defconfig

There are already Kconfig options for SPI flash drivers, but we
have not moved them from config.h to defconfig files. This commit
does this in a batch.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/configs/C29XPCIE_NAND_defconfig b/configs/C29XPCIE_NAND_defconfig
index 5cc1b46..bef3771 100644
--- a/configs/C29XPCIE_NAND_defconfig
+++ b/configs/C29XPCIE_NAND_defconfig
@@ -5,6 +5,8 @@
 CONFIG_TPL=y
 CONFIG_SYS_EXTRA_OPTIONS="C29XPCIE,36BIT,NAND"
 CONFIG_SPI_FLASH=y
+CONFIG_SPI_FLASH_EON=y
+CONFIG_SPI_FLASH_SPANSION=y
 CONFIG_NETDEVICES=y
 CONFIG_E1000=y
 CONFIG_SYS_NS16550=y