autotest.sh: load block RAM disk module

This provides /dev/ram0 when available so that we can have a convenient
blcok disk to test the Linux AIO backend against.

Change-Id: I557dae4dcba918838f55f85cd5981922d765d40e
Signed-off-by: Daniel Verkamp <daniel.verkamp@intel.com>
Reviewed-on: https://review.gerrithub.io/385297
Tested-by: SPDK Automated Test System <sys_sgsw@intel.com>
Reviewed-by: Ben Walker <benjamin.walker@intel.com>

autotest.sh

@@ -54,6 +54,9 @@ if [ $(uname -s) = Linux ]; then
 	for dev in $devs; do
 		parted -s /dev/$dev mklabel msdos
 	done
+
+	# Load RAM disk driver if available
+	modprobe brd || true
 fi
 timing_exit cleanup