omap: Fix access to already released memory in clk_debugfs_register_one()

I have found an access to already released memory in
clk_debugfs_register_one() function.

Signed-off-by: Marek Skuczynski <mareksk7@gmail.com>
Acked-by: Paul Walmsley <paul@pwsan.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>