ernel: support task's adj rbtree

Add (or del) a task to (or from) task's adj rbtree
when a task is created or exit.
Change-Id: Ic63e03355a1fed8c500097bad223c59c742a2346
Signed-off-by: Hong-Mei Li <a21834@motorola.com>
Signed-off-by: Yi-wei Zhao <gbjc64@motorola.com>
Reviewed-on: http://gerrit.mot.com/701207


SLTApproved: Slta Waiver <sltawvr@motorola.com>
Tested-by: Jira Key <jirakey@motorola.com>
Submit-Approved: Jira Key <jirakey@motorola.com>
Reviewed-on: http://gerrit.mot.com/727656


SME-Granted: SME Approvals Granted
Reviewed-by: Sheng-Zhe Zhao <a18689@motorola.com>

Used: https://bitbucket.org/arter97/android_kernel_samsung_exynos7420/commits/7e2384ab24be5b365dfd9090f50daf952404af04