remoteproc: zynqmp_r5_remoteproc: use shared interrupt

Use IRQF_SHARED for IPI interrupt since IPI interrupt is
shared with difference sources.
For example two instances of this driver where one target RPU0 and
the second RPU1.

Signed-off-by: Wendy Liang <jliang@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>