qemu-options.hx: Fix reversed description of icount sleep behavior

qemu-options.hx: Fix reversed description of icount sleep behavior

The documentation for the -icount option incorrectly describes the behavior
of the sleep suboption. Based on the actual implementation and system
behavior, the effects of sleep=on and sleep=off were inadvertently reversed.
This commit updates the description to reflect their intended functionality.

Cc: qemu-stable@nongnu.org
Fixes: fa647905e6ba ("qemu-options.hx: Fix minor issues in icount documentation")
Signed-off-by: Ethan Chen <ethan84@andestech.com>
Message-id: 20250606095728.3672832-1-ethan84@andestech.com
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>