mfd: tps65217: Fix mismatched interrupt number

Enum value of 'tps65217_irq_type' is not matched with DT parsed hwirq
number[*].

The MFD driver gets the IRQ data by referencing hwirq, but the value is
different. So, irq_to_tps65217_irq() returns mismatched IRQ data.
Eventually, the power button driver enables not PB but USB interrupt
when it is probed.

According to the TPS65217 register map[**], USB interrupt is the LSB.
This patch defines synchronized IRQ value.

[*]  include/dt-bindings/mfd/tps65217.h
[**] http://www.ti.com/lit/ds/symlink/tps65217.pdf



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