Resolves warning from Oracle Parfait static analyser:
Warning: Impossible or redundant condition
Impossible or redundant condition [impossible-redundant-condition]:
Condition 'dev != NULL' of branch is determined by previous branch
at line 270 of dix/devices.c in function 'AddInputDevice'.
Condition 'dev != NULL' from this branch implies following branch is always true at line 262
Fixes: commit 493ad83323
Signed-off-by: Alan Coopersmith <alan.coopersmith@oracle.com>