habanalabs: move common function out of debugfs.c

A common function that is called from multiple places can't be
located in degugfs.c because that file is only compiled if
debugfs is enabled in the kernel config file.

This can lead to undefined symbol compilation error.

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Oded Gabbay <ogabbay@kernel.org>