fuzz: Avoid deprecated misuse of -drive if=sd

fuzz: Avoid deprecated misuse of -drive if=sd

qemu-fuzz-i386-target-generic-fuzz-sdhci-v3 uses -drive=sd where it
should use -drive if=none instead.  This prints a deprecation warning:

    $ ./build-oss-fuzz/DEST_DIR/qemu-fuzz-i386-target-generic-fuzz-sdhci-v3 -runs=1 -seed=1
    [ASan warnings snipped...]
--> i386: -drive if=sd,index=0,file=null-co://,format=raw,id=mydrive: warning: bogus if=sd is deprecated, use if=none
    INFO: Seed: 1
    [More normal output snipped...]

Support for this usage will be gone soon.  Adjust the test.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20210319132008.1830950-1-armbru@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>