ARM errata 798181 is applicable for OMAP5 based devices. So enable
the same in the build. Errata extract and workaround information
is as below.

On Cortex-A15 (r0p0..r3p2) the TLBI*IS/DSB operations are not
adequately shooting down all use of the old entries. The
ARM_ERRATA_798181 option enables the Linux kernel workaround
for this erratum which sends an IPI to the CPUs that are running
the same ASID as the one being invalidated.

Cc: Tony Lindgren <tony@atomide.com>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>