usb: dwc3: imx8mp: request irq after initializing dwc3

usb: dwc3: imx8mp: request irq after initializing dwc3

If IRQ occurs between calling  devm_request_threaded_irq() and
initializing dwc3_imx->dwc3, then null pointer dereference occurs
since dwc3_imx->dwc3 is used in dwc3_imx8mp_interrupt().

The patch puts registration of the interrupt handler after
initializing of neccesery data.

Found by Linux Driver Verification project (linuxtesting.org).

Reviewed-by: Fabio Estevam <festevam@gmail.com>
Acked-by: Felipe Balbi <balbi@kernel.org>
Signed-off-by: Nadezda Lutovinova <lutovinova@ispras.ru>
Link: https://lore.kernel.org/r/20210819154818.18334-1-lutovinova@ispras.ru
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>