msm: mdss: return error -E2BIG when per pipe bandwidth check fails

In current implementation, it is possible that user-space tries to
configure pipe beyond its bandwidth (BW) limits. When driver detects this
condition, in few use-cases it can return -EINVAL which is not the proper
representation of the error and can lead to incorrect behavior from
user-space process. Correct this by always returning -E2BIG error
whenever per pipe BW check fails.

Change-Id: I90f429ad0bafd5bb5ec6da66d75d44ec48c0f299
Signed-off-by: Ujwal Patel <ujwalp@codeaurora.org>