ANDROID: export of_find_gpio.

In the process of driver development,the function of of_find_gpio is frequently utilized.
Currently, it is desired to export this function within the GKI kernel.

Bug: 409674606
Bug: 410433434
Bug: 417129415

Change-Id: I7c4bc8ab88a9597111cad9541b962490480f03d8
Signed-off-by: Xiong Liang <xiongliang@xiaomi.com>
(cherry picked from commit 9be2a46a)
(cherry picked from commit 7bcc01f7)