mfd: sec: Add support for S2MPS14

Add support for S2MPS14 PMIC device to the MFD sec-core driver.
The S2MPS14 is similar to S2MPS11 but it has fewer regulators, two
clocks instead of three and a little different registers layout.

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