DRA7: fix ABB efuse offset for OPP_NOM

commit 194dd74a
(DRA7: add ABB setup for MPU voltage domain)

Made an offset typo error by using 0x4A003B24 as the efuse offset
for OPP_NOM. As per TI documentation, 0x4A003B24 is for OPP_OD, and
0x4A003B20 is for OPP_NOM. Fix the same.

Reported-by: Praveen Rao <prao@ti.com>
Signed-off-by: Nishanth Menon <nm@ti.com>