usb: chipidea: fix precedence bug in ci_requests_show()

The intent here was to have parenthesis around the (ci->hw_ep_max / 2)
so that it counts like "0 1 2 0 1 2".  In the current code, the mod
operation happens first so it counts like "0 0 1 1 2 2".

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
[rebased on top of debug.c changes]
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>