tests/qtest: bios-tables-test: Adapt the case for win32

tests/qtest: bios-tables-test: Adapt the case for win32

Single quotes in the arguments (oem_id='CRASH ') are not removed in
the Windows environment before it is passed to the QEMU executable.
The space in the argument causes the "-acpitable" option parser to
think that all of its parameters are done, hence it complains:

  '-acpitable' requires one of 'data' or 'file'

Change to use double quotes which works fine on all platforms.

Also /dev/null does not work on win32, and nul should be used.

Signed-off-by: Bin Meng <bin.meng@windriver.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Message-Id: <20220925113032.1949844-39-bmeng.cn@gmail.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>