ARM: OMAP2+: craneboard: support the TPS65910 PMU

 This patch supports the TPS65910 PMU function on the AM3517 Craneboard.
 The IRQ pin, SYS_NIRQ is dedicated connection between the AM3517 and
 the TPS65910 PMU.
 To handle the PMU IRQs, mux configuration is required.

 Platform data configuration:
 .IRQ number : SYS_NIRQ (M_IRQ_7)
 .External clock source : external 32KHz clock is connected

Signed-off-by: Milo(Woogyom) Kim <milo.kim@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>