[qemu] Fix floppy boot with latest SeaBIOS

See https://www.mail-archive.com/qemu-devel@nongnu.org/msg638785.html

qemu.sh

@@ -29,6 +29,6 @@ HOSTFWD="-net user"
 
 SERIAL="-chardev pty,id=chardev1 -device isa-serial,chardev=chardev1,id=serial1"
 
-$QEMU -nodefaults -name ELKS -monitor stdio -machine isapc -cpu 486 -m 1M \
+$QEMU -nodefaults -name ELKS -machine isapc -cpu 486,tsc -m 1M \
 $KEYBOARD -display sdl -vga std -rtc base=utc $SERIAL \
 -net nic,model=ne2k_isa $HOSTFWD $NETDUMP -fda $IMAGE $@