DBG_CMD_NUM is the number of commands, not the actual bytes of
data for printing.

Also remove the duplicated DBG_CMD_NUM definition.
Reported-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: NBing Zhao <bzhao@marvell.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>