OMAP3+: voltage: remove spurious pr_notice for debugfs

cat of debugfs entry for vp_volt provides voltage. The additional pr_notice
is just spam on console and provides no additional information.

Signed-off-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Kevin Hilman <khilman@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>