Found by gcc -Wlogicalops:

sis_driver.c: In function 'SiS_CheckModeCRT2':
sis_driver.c:13754:5: warning: logical 'and' of mutually exclusive tests is always false [-Wlogical-op]
sis_driver.c:13755:6: warning: logical 'and' of mutually exclusive tests is always false [-Wlogical-op]
sis_driver.c:13756:6: warning: logical 'and' of mutually exclusive tests is always false [-Wlogical-op]
sis_driver.c:13758:5: warning: logical 'and' of mutually exclusive tests is always false [-Wlogical-op]
sis_driver.c:13759:6: warning: logical 'and' of mutually exclusive tests is always false [-Wlogical-op]

Signed-off-by: Alan Coopersmith <alan.coopersmith@oracle.com>
Reviewed-by: Gaetan Nadon <memsize@videotron.ca>