rpm: Fix FILES_${PN}

In a recent commit, the FILES expression for rpm accidently moved a
large portion of rpm-build into rpm:

http://git.yoctoproject.org/cgit.cgi/poky/commit/?id=2e557556e03f4e86795cf331ccf06acd4c373045

Since rpm-build requires perl, this caused a number of build failures
when the rpm-build package was attempted to be used since it references
/usr/bin/perl. This commit restores the previous contents of the rpm
package.

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>