msm: fb: add mdp foot switch for multiple splash displays

If there are multiple splash displays enabled in LK, mdp foot switch
needs to perform multiple times. Otherwise, clock resources are not
enabled/disabled symmetrically.

Change-Id: Iaca1163f44883be9e027460c48bd0ebc0ec2266a
Signed-off-by: Camus Wong <camusw@codeaurora.org>