package/checkpolicy: rename variable

package/checkpolicy: rename variable

We use package names as poor-man's namespace, so fix that.

Reported by utils/check-package.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: Adam Duskett <aduskett@gmail.com>
Cc: Clayton Shotwell <clayton.shotwell@rockwellcollins.com>
Cc: Matt Weber <matthew.weber@rockwellcollins.com>
[Thomas: use CHECKPOLICY_MAKE_OPTS instead of
CHECKPOLICY_TARGET_MAKE_OPTS, as it is more consistent with
HOST_CHECKPOLICY_MAKE_OPTS being used for the host variant.]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>