android: binder: refactor binder_transact()

Moved handling of fixup for binder objects,
handles and file descriptors into separate
functions.

Change-Id: If68c2d93c3a42765cefda40dc807b39f6ab774c2
Signed-off-by: Martijn Coenen <maco@google.com>
Git-commit: 6ea3f184
Git-repo: https://git.linaro.org/kernel/linux-linaro-stable


Signed-off-by: Neeraj Upadhyay <neeraju@codeaurora.org>