xtensa: replace setup_irq() by request_irq()

request_irq() is preferred over setup_irq(). Invocations of setup_irq()
occur after memory allocators are ready.

Per tglx[1], setup_irq() existed in olden days when allocators were not
ready by the time early interrupts were initialized.

Hence replace setup_irq() by request_irq().

[1] https://lkml.kernel.org/r/alpine.DEB.2.20.1710191609480.1971@nanos



Signed-off-by: afzal mohammed <afzal.mohd.ma@gmail.com>
Message-Id: <20200304004112.3848-1-afzal.mohd.ma@gmail.com>
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>