serialqueue: Tune MIN_REQTIME_DELTA timing

The MIN_REQTIME_DELTA parameter controls when the host will flush
incomplete message blocks to the mcu.  If the message had a target
time less than 250ms it would result in a flush even if a message
block was not completely full.

In the situation where the host generates lots of queue_step commands
to the point that it fills the mcu move_queue, then it would be
possible for individual queue_step commands to become eligible for
transmit only microseconds apart.  It could also lead to a situation
where the target time was less than 250ms in the future.  The result
could lead to many small message blocks as each became flushed
individually.

Tune the MIN_REQTIME_DELTA to 100ms to reduce the chance of this.

Signed-off-by: Kevin O'Connor <[email protected]>

Author: KevinOConnor

klippy/chelper/serialqueue.c

@@ -107,7 +107,7 @@ struct serialqueue {
 #define MIN_RTO 0.025
 #define MAX_RTO 5.000
 #define MAX_PENDING_BLOCKS 12
-#define MIN_REQTIME_DELTA 0.250
+#define MIN_REQTIME_DELTA 0.100
 #define MIN_BACKGROUND_DELTA 0.005
 #define IDLE_QUERY_TIME 1.0