mdss: mdp3: Remove scaling by 1 for ppp composition

Scaling by 1 logic was complicated. After trying to understand
what use cases we were preventing with this check, we verified that
ppp is actually able to handle scaling by 1 with hw team. There
is no need for this check.

Change-Id: I9f3cda5e61740fffdbda92dc768a98796b9a8238
Signed-off-by: Terence Hampson <thampson@codeaurora.org>