msm: mdss: Do not consider solid fill request in bandwidth logic

MDP_SOLID_FILL request does not require any data fetch on the bus,
so do not consider it in the optimal bandwidth logic.

Change-Id: I7ddfde78d94a42cfeba6aa0af7e805eba95bc699
Signed-off-by: Sushil Chauhan <sushilchauhan@codeaurora.org>