fix typos "wich" -> "which"

Signed-off-by: Uwe Zeisberger <zeisberg@informatik.uni-freiburg.de>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
diff --git a/drivers/video/sstfb.c b/drivers/video/sstfb.c
index 99921df..8c1a8b5 100644
--- a/drivers/video/sstfb.c
+++ b/drivers/video/sstfb.c
@@ -32,7 +32,7 @@
 
 -TODO: at one time or another test that the mode is acceptable by the monitor
 -ASK: Can I choose different ordering for the color bitfields (rgba argb ...)
-      wich one should i use ? is there any preferred one ? It seems ARGB is
+      which one should i use ? is there any preferred one ? It seems ARGB is
       the one ...
 -TODO: in  set_var check the validity of timings (hsync vsync)...
 -TODO: check and recheck the use of sst_wait_idle : we don't flush the fifo via