tests/vm: increased max timeout for vm boot.

tests/vm: increased max timeout for vm boot.

Add change to increase timeout waiting for VM to boot.
Needed for some emulation cases where it can take longer
than 5 minutes to boot.

Signed-off-by: Robert Foley <robert.foley@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Peter Puhov <peter.puhov@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20200219163537.22098-4-robert.foley@linaro.org>
Message-Id: <20200303150622.20133-4-alex.bennee@linaro.org>