staging: tidspbridge - move shared memory iommu maps to tiomap3430.c

Now iommu maps of shared memory segments are done in
bridge_brd_start and unmaped in bridge_brd_stop.

Signed-off-by: Fernando Guzman Lugo <x0095840@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>