a38x: add special GPIO callback routine example for customer board

gpp_callback is a generic place holder routine for special GPIO pull-up/sown sequence
this routine is called as the final step of mvBoardEnvInit flow
- Added empty routine stub for customer0 board, as an example for portine procedure

Change-Id: I1fbc7fb424c6bc329cd5f168969ca81502a9e020
Signed-off-by: Omri Itach <omrii@marvell.com>
Reviewed-on: http://vgitil04.il.marvell.com:8080/24972
Reviewed-by: Hanna Hawa <hannah@marvell.com>
Tested-by: Star_Automation <star@marvell.com>
Reviewed-by: Lior Amsalem <alior@marvell.com>
2 files changed