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

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().

Fixes: 5000d37042a6 ("dmaengine: sh: Add DMAC driver for RZ/G2L SoC")
Cc: stable@vger.kernel.org
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Tested-by: John Madieu <john.madieu.xa@bp.renesas.com>
Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
Tested-by: Tommaso Merciai <tommaso.merciai.xr@bp.renesas.com>
Link: https://patch.msgid.link/20260526084710.3491480-2-claudiu.beznea@kernel.org
Signed-off-by: Vinod Koul <vkoul@kernel.org>