ARM: OMAP2+: wakeupgen: AM43x adaptation

AM43x has 224 interrupts and 7 banks, make it as maximum values. Keep
default values as earlier, if am43x is detected, update interrupts and
banks accordingly.

Also AM43x has only one cpu, ensure that clearing bitmask at wakeupgen
is done only for the single existing cpu, existing code assumes that
there are two cpu's.

If bitmask is cleared in wakeupgen for the nonexistent second cpu,
an imprecise abort happens as soon as Kernel switches to user space.
It was rootcaused by Sekhar Nori <nsekhar@ti.com>.

Signed-off-by: Afzal Mohammed <afzal@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>