clock: tegra21: fix a warning message

clock: tegra21: fix a warning message

Fix the warning message below in tegra21_plle_clk_enable():
    "pll_e hw sequencer is already on"

This message is printed when PLLE is under HW control and there is a
request to enable PLLE. When PLLE is under HW control, SW need to
ignore requests to enable or disable PLLE. This message is for
information only.

Bug 1691314

Change-Id: I45585d3b5d6e32320ac2e1dd6511fcf9e63dd504
Signed-off-by: TW Chiu <twchiu@nvidia.com>
Reviewed-on: http://git-master/r/820865
Reviewed-by: Automatic_Commit_Validation_User
GVS: Gerrit_Virtual_Submit
Reviewed-by: Mark Kuo <mkuo@nvidia.com>
Reviewed-by: WK Tsai <wtsai@nvidia.com>
Reviewed-by: Ashutosh Jha <ajha@nvidia.com>