Add QTest testcase for the Intel Hexadecimal

Add QTest testcase for the Intel Hexadecimal

'test.hex' file is a memory test pattern stored in Hexadecimal Object
Format.  It loads at 0x10000 in RAM and contains values from 0 through
255.

The test case verifies that the expected memory test pattern was loaded.

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Suggested-by: Steffen Gortz <qemu.ml@steffen-goertz.de>
Suggested-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Su Hang <suhang16@mails.ucas.ac.cn>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
[PMM: changed qtest_startf() to qtest_initf() to work with
 current master after the refactoring in commit 88b988c895e3c2]
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>