soc: qcom: fix spcom getting the file dentry

The struct file no longer has the f_dentry macro.
The dentry is fetched from the f_path->dentry.

Change-Id: I7508effec34074aeb5f2d388e00efd688bf1afe8
Signed-off-by: Amir Samuelov <amirs@codeaurora.org>