msm_fb: display: add checking y direction for alpha drop

Alpha is dropped when scaling with non repeat pixel method.
Both x and y direction of scaling need to be cehcked for
alpha dropped.

(cherry picked from commit f0d08071a4e97c9018b8e8def498e07720201da8)

Change-Id: I69b8969c878f8422efecea86f93749e0970b77bc
Signed-off-by: Kuogee Hsieh <khsieh@codeaurora.org>