firmware: arm_scmi: Do not use !! on boolean when setting msg->flags

Both pc->async_powercap_cap_set and ignore_dresp are already boolean.
Use of !! on them is obviously dubious.

Sparse reports:
drivers/firmware/arm_scmi/powercap.c:363:17: warning: dubious: x & !y
drivers/firmware/arm_scmi/powercap.c:363:17: warning: dubious: x & !y

Remove the unnecessary !! and get rid of the warning.
Reviewed-by: Cristian Marussi <cristian.marussi@arm.com>
Link: https://lore.kernel.org/r/20230921085257.3125744-1-sudeep.holla@arm.comSigned-off-by: Sudeep Holla <sudeep.holla@arm.com>

drivers/firmware/arm_scmi/powercap.c

@@ -360,8 +360,8 @@ static int scmi_powercap_xfer_cap_set(const struct scmi_protocol_handle *ph,
 	msg = t->tx.buf;
 	msg->domain = cpu_to_le32(pc->id);
 	msg->flags =
-		cpu_to_le32(FIELD_PREP(CAP_SET_ASYNC, !!pc->async_powercap_cap_set) |
-			    FIELD_PREP(CAP_SET_IGNORE_DRESP, !!ignore_dresp));
+		cpu_to_le32(FIELD_PREP(CAP_SET_ASYNC, pc->async_powercap_cap_set) |
+			    FIELD_PREP(CAP_SET_IGNORE_DRESP, ignore_dresp));
 	msg->value = cpu_to_le32(power_cap);
 
 	if (!pc->async_powercap_cap_set || ignore_dresp) {