irqchip: sirf: move from legacy mode to linear irqdomain

the series of patches for irqdomain core in 3.11 has broken sirf
irq which uses legacy mapping. all users fail in the new kernel
while setupping irq.

this patch moves to linear irqdomain and drop old legacy irqdomain
codes since we don't need it any more, and at the same time, it
also fixes the broken interrupts of sirfsoc in 3.11.

on the other hand, we actually only have 64 interrupt sources for
prima2 and atlas6, but there are 128 interrupt souces for marco
which uses GIC. in the legacy codes, sirf gpio also uses legacy
irqdomain, so to make gpio interrupt mapping not depend on the
prima2/atlas6/marco an use unified marco,we enlarge prima2/atlas6
interrupt number to 128. here we don't need this workaround any
more as sirf gpio also moved to linear mode before. so we move
SIRFSOC_NUM_IRQS back to 64 too.

Signed-off-by: Barry Song <Baohua.Song@csr.com>
Signed-off-by: Olof Johansson <olof@lixom.net>