package/image.bbclass: Fix multilib rprovides

package/image.bbclass: Fix multilib rprovides

allarch multilib recipes are meant to provide a list of different multilib variants.
Unfortunately since the pkgdata also has mappings for these, they get mapped back to
the original package name which means the effect is undone at package creation time
when the remapping code is called.

This patch adds in a conditional to break that chain meaning the packages get
the correct RPROVIDES and image builds work correctly with opkg.

[YOCTO #3453]

(From OE-Core rev: 1a1927f8a04fe0a2b3b853ebdd33ccb807f00b59)

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