lib/device_map: rpi3: blacklist ARM32
lib/device_map: rpi3: blacklist ARM32

Current kCI labs with rpi3 are all using ARM64 for manline u-boot with
mainline kernel, and rpi3 u-boot is not currently able to boot ARM32
kernels.

To fix, blacklist ARM32 jobs.

Signed-off-by: Kevin Hilman <f9849b02abe18c1ece6bd40346458ed53f49d31b@baylibre.com>

kernelci/lava-ci-staging,kernelci/lava-ci-staging,kernelci/lava-ci-staging