regmap: 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.

The debugfs core will warn if a file or directory can not be created, so
there's no need to duplicate the warning, nor really do anything else.

Cc: Mark Brown <broonie@kernel.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/r/20190731132923.GA13829@kroah.com


Signed-off-by: Mark Brown <broonie@kernel.org>