[qemu] error when modprobing loop should not be fatal

Created by: pavelmachek

In losetup.py, I suggest something like this: I do have loop built-in, so modprobe fails, but loop is still usable.

--- a/pmb/install/losetup.py
+++ b/pmb/install/losetup.py
@@ -27,7 +27,10 @@ import pmb.chroot
 
 
 def init(args):
-    pmb.helpers.run.root(args, ["modprobe", "loop"])
+    try:
+        pmb.helpers.run.root(args, ["modprobe", "loop"])
+    except:
+        print("Can't modprobe loop, perhaps it is built-in?")