Revert "nvmem: core: remove nvmem_config wp_gpio"

This reverts commit 6d9fa3ff which is
commit 569653f0 upstream.

It breaks the kernel abi and is not needed in Android systems at this
point in time.

If it's wanted, it can come back in an abi-safe way in the future.

Bug: 161946584
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: I75ba9754039f961a77c1d04f22c9110287cd8efe