ARM: dts: dra7: Fix efuse register size for ABB

Fix a typo in DRA7 dtsi where 12 bytes are needed for register
description of ABB efuse registers, however only 8 bytes are provided
to map. For some weird reason, this does not generate abort at offset
0x8, probably due to default maps already provided in io.c for the bus
register ranges.

Reported-by: Matt Gessner <Matt.Gessner@windriver.com>
Reported-by: Suman Anna <s-anna@ti.com>
Signed-off-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>