scripts: openocd.sh: align usage of OPENOCD_*_CMD variables

OPENOCD_PRE_CMD, OPENOCD_POST_CMD variables require adding
'-c' in front of an actual OpenOCD command. This is in contrary
to other OPENOCD_*_CMD varialbles which specify OpenOCD commands
directly. This patch aligns usage of various OPENOCD_*_CMD variables.
It is no longer required to add '-c' in front of OPENOCD_PRE_CMD,
OPENOCD_POST_CMD variables.

Change-Id: I276fab00b099694c83c3bf74aa5dd59c8d6a308b
Signed-off-by: Piotr Mienkowski <piotr.mienkowski@gmail.com>
8 files changed