test/rootfs: Increase size of sparsefile to 32GB
test/rootfs: Increase size of sparsefile to 32GB

Signed-off-by: Joseph Glanville <aed65cdb66c1129f81e57d35b788d35820e08ea4@jpg.id.au>

lmars/flynn,lmars/flynn,lmars/flynn,philiplb/flynn,flynn/flynn,benbjohnson/flynn,philiplb/flynn,benbjohnson/flynn,flynn/flynn,benbjohnson/flynn,philiplb/flynn,flynn/flynn,benbjohnson/flynn,philiplb/flynn,lmars/flynn,flynn/flynn,benbjohnson/flynn,flynn/flynn,philiplb/flynn,benbjohnson/flynn,lmars/flynn