extcon: max8997: Fix NULL pointer exception on missing pdata

commit dfee4111febf3d9ef3a640b2cd6205c75f4e7e3d upstream.

Fix NULL pointer exception when platform data is not supplied. The
driver dereferenced pdata pointer where it could be NULL.

Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Fixes: 810d601f
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>