Revert "ANDROID: f2fs: fixup ABI break due to reserved_pin_section"

This reverts commit 4317f0ae.

It is the time to allow kabi-breaks, so it is safe to revert this
change.

Bug: 428889879
Cc: Paul Lawrence <paullawrence@google.com>
Cc: Giuliano Procida <gprocida@google.com>
Cc: Todd Kjos <tkjos@google.com>
Cc: Carlos Llamas <cmllamas@google.com>
Change-Id: I298c7c989c7df0f9e57882d4b289e3391a489627
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>