usb: dwc2: host: don't use dma_alloc_coherent with irqs disabled

Align buffer must be allocated using kmalloc since irqs are disabled.
Coherency is handled through dma_map_single which can be used with irqs
disabled.

Reviewed-by: Julius Werner <jwerner@chromium.org>
Acked-by: John Youn <johnyoun@synopsys.com>
Signed-off-by: Gregory Herrero <gregory.herrero@intel.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>