powerpc: Use irq_desc_get_xxx() to avoid redundant lookup of irq_desc

Use irq_desc_get_xxx() to avoid redundant lookup of irq_desc while we
already have a pointer to corresponding irq_desc.

Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

diff --cc arch/powerpc/platforms/52xx/mpc52xx_gpt.c
Simple merge

diff --cc arch/powerpc/platforms/cell/axon_msi.c
Simple merge

diff --cc arch/powerpc/platforms/embedded6xx/hlwd-pic.c
Simple merge

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

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