target/xscale: change prototype of xscale_display_instruction()

target/xscale: change prototype of xscale_display_instruction()

To prepare for handling TCL return values consistently, all calls
to command_print/command_print_sameline should be ready to switch
to CMD as first parameter.

Change prototype of xscale_display_instruction() and of
xscale_analyze_trace() to pass CMD instead of CMD_CTX.

This change was part of http://openocd.zylin.com/1815 from Paul
Fertser and has been extracted and rebased to simplify the review.

Change-Id: I8420f19c1b2ff0d2a2f2a8d3627767f7acda437c
Signed-off-by: Paul Fertser <fercerpav@gmail.com>
Signed-off-by: Tomas Vanek <vanekt@fbl.cz>
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-on: http://openocd.zylin.com/5065
Tested-by: jenkins