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_defconfig b/configs/C29XPCIE_defconfig
index 022325e..373db16 100644
--- a/configs/C29XPCIE_defconfig
+++ b/configs/C29XPCIE_defconfig
@@ -3,6 +3,8 @@
 CONFIG_TARGET_C29XPCIE=y
 CONFIG_SYS_EXTRA_OPTIONS="C29XPCIE,36BIT"
 CONFIG_SPI_FLASH=y
+CONFIG_SPI_FLASH_EON=y
+CONFIG_SPI_FLASH_SPANSION=y
 CONFIG_NETDEVICES=y
 CONFIG_E1000=y
 CONFIG_SYS_NS16550=y