checkpatch: add list of typedef used in OpenOCD

The new checkpatch from Linux kernel does not recognizes the
specific types used in OpenOCD, e.g. "fd_set" and "Jim_Obj".
As consequence, it consider "fd_set" as the name of a variable,
then misinterpret the asterisk for the pointer "fd_set *" as a
multiplication, thus suggest to add a space after the asterisk
and replace "fd_set *x" with "fd_set * x".

Let checkpatch recognize the typedef used in OpenOCD.

Change-Id: Ibc295e6a8b47ffa88b50a6d510b7970760e5199d
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-on: https://review.openocd.org/c/openocd/+/5607
Tested-by: jenkins