sis900 warning fixes

drivers/net/sis900.c: In function 'sis900_reset_phy':
drivers/net/sis900.c:972: warning: 'status' may be used uninitialized in this function
drivers/net/sis900.c: In function 'sis900_check_mode':
drivers/net/sis900.c:1431: warning: 'status' may be used uninitialized in this function
drivers/net/sis900.c: In function 'sis900_timer':
drivers/net/sis900.c:1467: warning: 'status' may be used uninitialized in this function

Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jeff Garzik <jeff@garzik.org>