[PARISC] Update CREDITS entries

Update Randolph Chung's location, and add Thibaut Varene.

Signed-off-by: Randolph Chung <tausq@parisc-linux.org>
Signed-off-by: Thibaut Varene <varenet@parisc-linux.org>
Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>