mfd: fsl-imx25-tsadc: Fix module autoload when registered via OF

If the driver is built as a module, autoload won't work because the module
alias information is not filled. So user-space can't match the registered
device with the corresponding module.

Export the module alias information using the MODULE_DEVICE_TABLE() macro.

Before this patch:

$ modinfo drivers/mfd/fsl-imx25-tsadc.ko | grep alias
alias:          platform:mx25-tsadc

After this patch:

$ modinfo drivers/mfd/fsl-imx25-tsadc.ko | grep alias
alias:          platform:mx25-tsadc
alias:          of:N*T*Cfsl,imx25-tsadcC*
alias:          of:N*T*Cfsl,imx25-tsadc

Signed-off-by: Javier Martinez Canillas <javier@osg.samsung.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>