dt-bindings: mfd: Provide human readable defines for TPS65217 interrupts

TPS65217 supports three interrupt sources. This patch enables assigning
each IRQ number in the charger and power button node. Then corresponding
IRQ will be requested by each driver.

Signed-off-by: Milo Kim <woogyom.kim@gmail.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>