mfd: tps65910: Fix regmap_irq_chip_data leak on mfd_add_devices fail

The tps65910_i2c_probe() allocates regmap_irq_chip in
tps65910_irq_init() but it does not clean this up in case of
mfd_add_devices() failure.

Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>