fbdev: TV_PALN bit set twice in sisfb_detect_VB_connect()

The TV_PALN bit was tested twice, replace one by TV_PALM.

Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Cc: Thomas Winischhofer <thomas@winischhofer.net>
Cc: Krzysztof Helt <krzysztof.h1@poczta.fm>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>