mfd: 88pm800: Fix I2C device resource leak if probe fails

mfd: 88pm800: Fix I2C device resource leak if probe fails

During probe the driver allocates two dummy I2C devices for subchips in
function pm800_pages_init(). Additionally this function allocates
regmaps for these subchips. If any of these steps fail then these dummy
I2C devices are not freed and resources leak.

On pm800_pages_init() fail the driver must call pm800_pages_exit() to
unregister dummy I2C devices.

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