ARM: OMAP2: Fix up interconnect barrier initialization for DRA7

The following commits:
commit 3fa609755c11 ("ARM: omap2: restore OMAP4 barrier behaviour")
commit f746929ffdc8 ("Revert "ARM: OMAP4: remove dead kconfig option OMAP4_ERRATA_I688"")
and
commit ea827ad5ffbb ("ARM: DRA7: Provide proper IO map table")
came in around the same time, unfortunately this seem to have missed
initializing the barrier for DRA7 platforms - omap5_map_io was reused
for dra7 till it was split out by the last patch. barrier_init
needs to be hence carried forward as it is valid for DRA7 family of
processors as they are for OMAP5.

Fixes: ea827ad5ffbb7 ("ARM: DRA7: Provide proper IO map table")
Cc: [e-mail] # v4.1+
Reported-by: Laurent Pinchart <[e-mail]>
Reported-by: Tomi Valkeinen <[e-mail]>
Cc: Russell King <[e-mail]>
Signed-off-by: Nishanth Menon <[e-mail]>
Reviewed-by: Laurent Pinchart <[e-mail]>
Signed-off-by: Tony Lindgren <[e-mail]>

arch/arm/mach-omap2/io.c

···
 void __init dra7xx_map_io(void)
 {
 	iotable_init(dra7xx_io_desc, ARRAY_SIZE(dra7xx_io_desc));
+	omap_barriers_init();
 }
 #endif
 /*