dmaengine: sh: rz-dmac: Move interrupt request after everything is set up

In the Linux kernel, the following vulnerability has been resolved: dmaengine: sh: rz-dmac: Move interrupt request after everything is set up Once the interrupt is requested, the interrupt handler may run immediately. Since the IRQ handler can access channel->ch_base, which is initialized only after requesting the IRQ, this may lead to invalid memory access. Likewise, the IRQ thread may access uninitialized data (the ld_free, ld_queue, and ld_active lists), which may also lead to issues. Request the interrupts only after everything is set up. To keep the error path simpler, use dmam_alloc_coherent() instead of dma_alloc_coherent().