drm/exynos: fix a timeout loop

We were trying to print an error message if we timed out here, but the
loop actually ends with "tries" set to UINT_MAX and not zero.  Fix this
by changing from tries-- to --tries.

A for loop would actually be the most natural way to do this.  My fix
means we only loop 99 times instead of 100 but that's probably ok.

Fixes: a696394c

 ('drm/exynos: mixer: simplify loop in vp_win_reset()')
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Tobias Jakobi <tjakobi@math.uni-bielefeld.de>
Signed-off-by: Inki Dae <inki.dae@samsung.com>