spi: davinci: switch to managed controller allocation

Summary

In the Linux kernel, the following vulnerability has been resolved: spi: davinci: switch to managed controller allocation The controller is allocated with the non-managed spi_alloc_host() while the interrupt is registered with devm_request_threaded_irq(). During removal, spi_bitbang_stop() only unregisters the controller; the subsequent spi_controller_put() then frees the controller together with its embedded davinci_spi devdata, which is the IRQ handler's dev_id. The devm_request_threaded_irq() release action (free_irq()), which drains the handler, does not run until after .remove() returns. A late or latched interrupt can therefore reach davinci_spi_irq() and dereference already-freed memory. Switch to devm_spi_alloc_host() so that the devres LIFO order releases the controller only after free_irq() has drained the handler, and drop the now-redundant spi_controller_put() from .remove(). The probe error path is simplified to direct returns. The clock is acquired with devm_clk_get_enabled(), which is registered after the IRQ and thus released before it by the devres LIFO order. Drain the interrupt explicitly with devm_free_irq() before disabling the controller so that a late interrupt cannot access the registers of a clock-gated controller. This issue was found by an in-house static analysis tool.