mmc: davinci: Don't strip remove function when driver is builtin

In the Linux kernel, the following vulnerability has been resolved:

mmc: davinci: Don't strip remove function when driver is builtin

Using __exit for the remove function results in the remove callback being

discarded with CONFIG_MMC_DAVINCI=y. When such a device gets unbound (e.g.

using sysfs or hotplug), the driver is just removed without the cleanup

being performed. This results in resource leaks. Fix it by compiling in the

remove callback unconditionally.

This also fixes a W=1 modpost warning:

WARNING: modpost: drivers/mmc/host/davinci_mmc: section mismatch in

reference: davinci_mmcsd_driver+0x10 (section: .data) ->

davinci_mmcsd_remove (section: .exit.text)