rootfs_rpm: Escape the backtick to ensure the ls runs on the target

This change ensures that the ls /etc/rpm-postinsts runs in the target
at first boot time, rather than at the creation time of the script on
the host.

This was causing the following error in the rootfs log:

+ install -d /srv/ssd/sgw/machines/fri2/tmp/work/fri2-poky-linux/core-image-minimal/1.0-r0/rootfs//etc/rcS.d
+ i=
+ ls /etc/rpm-postinsts/
ls: cannot access /etc/rpm-postinsts/: No such file or directory

Signed-off-by: Saul Wold <sgw@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
module.bbclass: Don't add pkg_postinst/pkg_prerm to all packages in recipe

The code in module.bbclass was appending the pkg_postinst and
pkg_prerm to all packages that are part of a given recipe, meaning
that the -lic, -dev, -doc, ... packages all got the scriptlet
This change uses  only which macthes with the RDEPENDS and FILES
already used in module.bbclass.

The failure was that rootfs creation would fail due to the -lic package
being installed before the kernel and the script would fail.

[YOCTO #3803]

Signed-off-by: Saul Wold <sgw@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>