package_manager.py: make rpm install mutilib pkgs corectly

package_manager.py: make rpm install mutilib pkgs corectly

When configure multilib, "bitbake <image_bb> -c populate_sdk" should
install all arch toolchains (for example, 32 and 64bit), but rpm not
handle the multilib requires correctly, for example:
lib32-packagegroup-core-standalone-sdk-target requires lib32-libc6, rpm
may pull in libc6 rather than lib32-libc6, there are the similar issue
when:

IMAGE_INSTALL_append += "lib32-packagegroup-foo foo"

Use bitbake to expand the RDEPENDS will fix the problem since bitbake
knows mlprefix and handle it well, but rpm doesn't.

This patch only affects when:
IMAGE_INSTALL = "lib32-foo foo"
Doesn't affect:
IMAGE_INSTALL = "lib32-foo1 lib32-foo2"
Or:
IMAGE_INSTALL = "foo1 foo2"

[YOCTO #8089]

Signed-off-by: Robert Yang <liezhi.yang@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>