scripts: sercomm-pid.py: use uppercase hwid in pid
Sercomm uses uppercase for hexadecimal representation of the device
hardware IDs in factory image PID. This commit brings the sercomm-pid.py
script into compliance with the original Sercomm algorithm.
Example
-------
+--------+-------------+-----------+-------------+
| Device | PID (before | PID | PID (after |
| HWID | the commit) | (Sercomm) | the commit) |
+--------+-------------+-----------+-------------+
| CPJ | 43 50 4a | 43 50 4A | 43 50 4A |
+--------+-------------+-----------+-------------+
Signed-off-by: Mikhail Zhilkin <csharper2005@gmail.com>