spi: Move SPI drivers to defconfig

There are already Kconfig options for SPI 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/P2041RDB_SPIFLASH_defconfig b/configs/P2041RDB_SPIFLASH_defconfig
index a038036..2264484 100644
--- a/configs/P2041RDB_SPIFLASH_defconfig
+++ b/configs/P2041RDB_SPIFLASH_defconfig
@@ -6,3 +6,4 @@
 CONFIG_NETDEVICES=y
 CONFIG_E1000=y
 CONFIG_SYS_NS16550=y
+CONFIG_FSL_ESPI=y