Removes rate limiting from kupload.sh

Commit 7123bcb0fcca9e39c35f4b67088b581cdf2fb50d changed the UART driver
to work around ZMODEM uploads waiting forever on the next rx_watermark
IRQ that would never come.

With this workaround, we no longer need to rate limit ZMODEM transfers
on the sender side.

Change-Id: I693dd3bca98f446739a1f01ba537543ffb5dd03e

kupload.sh

diff --git a/kupload.sh b/kupload.sh
index fdf44d6..eca26bd 100755
--- a/kupload.sh
+++ b/kupload.sh
@@ -1,10 +1,4 @@
 #!/bin/bash
 # ZMODEM upload to the Kata rz command over the pty simulating the UART
-#
-# sz is "send ZMODEM", while pv, "pipe viewer" is used for rate limiting.
-#
-# Severe rate limiting is needed to avoid the Renode UART simulation dropping
-# bytes when the RX FIFO is full, since it doesn't provide "hardware" flow
-# control.
 
-sz -O $1 < /tmp/term | pv -L 150 > /tmp/term
+sz -O $1 < /tmp/term > /tmp/term