extcon: realtek: fix NULL deref check in extcon_rtk_type_c_probe

In extcon_rtk_type_c_probe() devm_kzalloc() may return NULL but this
returned value is not checked.

Fixes: 8a590d73 ("extcon: add Realtek DHC RTD SoC Type-C driver")
Link: https://lore.kernel.org/lkml/20241025094650.253599-1-hanchunchao@inspur.com/


Signed-off-by: Charles Han <hanchunchao@inspur.com>
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>