ARM: DRA72: disable workaround for 801819

ARM: DRA72: disable workaround for 801819

DRA72x processor variants are single core and it does not export ACP[1].
Hence, we have no source for generating an external snoop requests which
appear to be key to the deadlock in DRA72x design.

Since we build the same image for DRA74x and DRA72x platforms, lets
runtime detect and disable the workaround (in favor of performance) on
DRA72x platforms.

[1] http://infocenter.arm.com/help/topic/com.arm.doc.ddi0438i/BABIAJAG.html

Suggested-by: Richard Woodruff <r-woodruff2@ti.com>
Suggested-by: Brad Griffis <bgriffis@ti.com>
Reviewed-by: Brad Griffis <bgriffis@ti.com>
Signed-off-by: Nishanth Menon <nm@ti.com>