Rename STATE_IN_BAND_SLEEP_ENABLED to QCA_IBS_ENABLED. The constant
represents a flag (multiple flags can be set at once), not a unique
state of the controller or driver.

Also make the flag an enum value instead of a pre-processor constant
(more flags will be added to the enum group by another patch).
Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
Reviewed-by: Balakrishna Godavarthi <bgodavar@codeaurora.org>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>