staging: android: binder: Fix use of euid

Task credentials were moved and must be accessed through task_struct.cred

Signed-off-by: J.R. Mauro <jrm8005@gmail.com>
Cc: Arve Hjønnevåg <arve@android.com>
Cc: Brian Swetland <swetland@google.com>
Cc: Robert Love <rlove@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>