OMAP4: DSI: Reset required disable-enable sequence

During the initialization of DSI,some times BTA
sent by OMAP DSI, was not receiving an BTA ACK.
To rectify this, we need to reset the DSI module
whenever we diable-enable the DSI module.

Change-Id: Ic2542970da06a121559a8cc700222881c60c025c
Signed-off-by: Sujeet Kumar Baranwal <s-baranwal@ti.com>