power: max17048: Add 18bit model soc calculation

power: max17048: Add 18bit model soc calculation

 Adding 18bit model soc calculation
 according to the model data bits
 Bug 1355408

Change-Id: If3499ed08390e882da52d7e0ef405715836a42cb
Signed-off-by: Venkat Reddy Talla <vreddytalla@nvidia.com>
Reviewed-on: http://git-master/r/279318
Reviewed-by: Automatic_Commit_Validation_User
Reviewed-by: Laxman Dewangan <ldewangan@nvidia.com>
(cherry picked from commit ef3812253f2954ff72a1e330aa6ea0080e63fc42)
Signed-off-by: Ajay Nandakumar <anandakumarm@nvidia.com>