package_rpm.bbclass: fix build multilib image failed when PR Server enabled

package_rpm.bbclass: fix build multilib image failed when PR Server enabled

1, In bitbake.conf
   PKGR ?= "${PR}${EXTENDPRAUTO}"
   EXTENDPKGV ?= "${EXTENDPKGEVER}${PKGV}-${PKGR}"
   RDEPENDS_${PN}-dev = "${PN} (= ${EXTENDPKGV})"

2, When PR Server is enabled, EXTENDPRAUTO is not none which means PKGR and PR
don't have the same value.

3, When multilib is enabled, RDEPENDS_${PN}-dev is not expanded correctly
which uses PR rather than PKGR in the versioned dependency string.

4, Make sure PKGR rather than PR in version string when do_package_rpm.

[YOCTO #4050]

Signed-off-by: Hongxu Jia <hongxu.jia@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>