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/am43xx_evm_ethboot_defconfig b/configs/am43xx_evm_ethboot_defconfig
index 9038702..04c808e 100644
--- a/configs/am43xx_evm_ethboot_defconfig
+++ b/configs/am43xx_evm_ethboot_defconfig
@@ -8,3 +8,4 @@
 # CONFIG_CMD_SETEXPR is not set
 CONFIG_SPI_FLASH=y
 CONFIG_SYS_NS16550=y
+CONFIG_TI_QSPI=y