15_ostree: don't assume kernel arch names

uname -m is not always the suffix of the kernel image. Debian uses
-686-pae, but uname -m would say i686. This creates an infinite loop in
Debian.

gnomeos/15_ostree

@@ -42,8 +42,7 @@ EOF
 EOF
 }
 
-machine=$(uname -m)
-kernels=$(echo /boot/vmlinuz-*.${machine})
+kernels=$(echo /boot/vmlinuz-*)
 while [ "x${kernels}" != x ]; do
   linux=`version_find_latest $kernels` >&2
   basename=`basename $linux`