clk: no need to check return value of debugfs_create functions

When calling debugfs functions, there is no need to ever check the
return value.  The function can work or not, but the code logic should
never do something different based on this.

This cleans up the init code a lot, and there's no need to return an
error value based on the debugfs calls, especially as it turns out no
one was even looking at that return value.  So it obviously wasn't that
important :)

Cc: Michael Turquette <mturquette@baylibre.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>