ARM: imx: Fix the removal of CONFIG_SPI option

Since 64546e9f ("ARM: imx_v6_v7_defconfig updates") and commit
0650f855 ("ARM: imx_v4_v5_defconfig: Select CONFIG_IMX_WEIM") CONFIG_SPI
selection was dropped by savedefconfig for imx_v4_v5_defconfig and
imx_v6_v7_defconfig.

In order to keep the same behaviour as previous kernel versions and avoid
regressions, let's add CONFIG_SPI option back.
Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>

arch/arm/configs/imx_v4_v5_defconfig

@@ -97,6 +97,7 @@ CONFIG_SERIAL_IMX_CONSOLE=y
 # CONFIG_HW_RANDOM is not set
 CONFIG_I2C_CHARDEV=y
 CONFIG_I2C_IMX=y
+CONFIG_SPI=y
 CONFIG_SPI_IMX=y
 CONFIG_SPI_SPIDEV=y
 CONFIG_GPIO_SYSFS=y

arch/arm/configs/imx_v6_v7_defconfig

@@ -158,6 +158,7 @@ CONFIG_I2C_CHARDEV=y
 CONFIG_I2C_ALGOPCF=m
 CONFIG_I2C_ALGOPCA=m
 CONFIG_I2C_IMX=y
+CONFIG_SPI=y
 CONFIG_SPI_IMX=y
 CONFIG_GPIO_SYSFS=y
 CONFIG_GPIO_MC9S08DZ60=y