ARM: Tegra: Fix PowerGate status logic

In the code we are reading value of PMC_PWRGATE_TOGGLE in reg variable.
But loop was checking for status variable. Fix the same

Change-Id: If18bf9ddcb403b60f084dee2edf3980e06ff2e3b
Signed-off-by: Bhavesh Parekh <bparekh@nvidia.com>
Reviewed-on: http://git-master/r/309991
Reviewed-by: Automatic_Commit_Validation_User
Reviewed-by: Prashant Gaikwad <pgaikwad@nvidia.com>
Reviewed-by: Bharat Nihalani <bnihalani@nvidia.com>
Tested-by: Bharat Nihalani <bnihalani@nvidia.com>

Conflicts:
	arch/arm/mach-tegra/powergate.c