ion: change ion_user_handle_t definition to int

Turn ion_user_handle_t to int. This change reflects the underlying type
returned by the ion driver.

Change-Id: I40390dae8138327769510525bf62e55877a4b37d
Signed-off-by: Rom Lemarchand <romlem@google.com>
Git-commit: dcd2da8015c7ac2da6f57fc0d8c15b80e44c4aed
Git-repo: http://android.googlesource.com/kernel/common/


[mitchelh@codeaurora.org: made changes to file in different location
 since we've already done the uapi split. Also, one function name was
 different due to some necessary patch re-ordering.]
Signed-off-by: Mitchel Humpherys <mitchelh@codeaurora.org>