powerpc: Constify irq_domain_ops

The irq_domain_ops are not modified by the driver and the irqdomain core
code accepts pointer to a const data.

Signed-off-by: Krzysztof Kozlowski <k.kozlowski.k@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

diff --cc arch/powerpc/sysdev/i8259.c
Simple merge

diff --cc arch/powerpc/sysdev/ipic.c
Simple merge

diff --cc arch/powerpc/sysdev/mpc8xx_pic.c
Simple merge

diff --cc arch/powerpc/sysdev/mpic.c
Simple merge

diff --cc arch/powerpc/sysdev/mv64x60_pic.c
Simple merge

diff --cc arch/powerpc/sysdev/qe_lib/qe_ic.c
Simple merge

diff --cc arch/powerpc/sysdev/tsi108_pci.c
Simple merge

diff --cc arch/powerpc/sysdev/uic.c
Simple merge

diff --cc arch/powerpc/sysdev/xics/xics-common.c
Simple merge

diff --cc arch/powerpc/sysdev/xilinx_intc.c
Simple merge