ARM: tegra: clock: Update Tegra3 cbus operations

ARM: tegra: clock: Update Tegra3 cbus operations

- Doubled PLLC (cbus parent) rate to make sure that cbus clients always
  have only even dividers.

- Added new shared bus user mode - SHARED_AUTO for user (like Host1x)
  that just follow the bus, but by itself does not require bus rate
  above the minimum.

Bug 895245

Signed-off-by: Alex Frid <afrid@nvidia.com>
(cherry picked from commit e95329c67d4efc424d3408b363e092c02c066ef7)
(cherry picked from commit 773e089f2ab676e9ea8afd7aaa0458654a3772d9)

Change-Id: Ie1488f38e3cb948d69738c2eef4ae9cd7ae0b47d
Reviewed-on: http://git-master/r/67011
Tested-by: Aleksandr Frid <afrid@nvidia.com>
Reviewed-by: Yu-Huan Hsu <yhsu@nvidia.com>
Rebase-Id: Rdd00a21fc2f58efdfeec5733c0307627da1fb430