package_rpm.bbclass: Should be using HOST_* not TARGET_*

package_rpm.bbclass: Should be using HOST_* not TARGET_*

When building target packages, HOST_OS and TARGET_OS are the same, as is the
VENDOR field.  However, when building an SDK this is not true.  The patch
corrects the oversight and switches to using the 'HOST' version and resolves
the issue of meta-mingw not working w/ the rpm packaging.

(From OE-Core rev: 0fa1eb5c1296a38b332b63d539608da7ef56c3c0)

Signed-off-by: Mark Hatle <mark.hatle@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>