powerpc/corenet: enable CONFIG_I2C_MUX and CONFIG_I2C_MUX_PCA954x

By default we enable CONFIG_I2C_MUX and CONFIG_I2C_MUX_PCA954x,
which are needed on T2080QDS, T4240QDS, B4860QDS, etc.
Signed-off-by: Shengzhou Liu <Shengzhou.Liu@freescale.com>
[scottwood@freescale.com: fixed subject line]
Signed-off-by: Scott Wood <scottwood@freescale.com>

arch/powerpc/configs/corenet32_smp_defconfig

@@ -116,6 +116,8 @@ CONFIG_NVRAM=y
 CONFIG_I2C=y
 CONFIG_I2C_CHARDEV=y
 CONFIG_I2C_MPC=y
+CONFIG_I2C_MUX=y
+CONFIG_I2C_MUX_PCA954x=y
 CONFIG_SPI=y
 CONFIG_SPI_GPIO=y
 CONFIG_SPI_FSL_SPI=y

arch/powerpc/configs/corenet64_smp_defconfig

@@ -109,6 +109,8 @@ CONFIG_SERIAL_8250_RSA=y
 CONFIG_I2C=y
 CONFIG_I2C_CHARDEV=y
 CONFIG_I2C_MPC=y
+CONFIG_I2C_MUX=y
+CONFIG_I2C_MUX_PCA954x=y
 CONFIG_SPI=y
 CONFIG_SPI_GPIO=y
 CONFIG_SPI_FSL_SPI=y