mfd: Add battery charger in tps65090 sub devs

TPS65090 supports the battery charging and hence adding
the device name in the list of TPS65090 children. Also
remove the tps65090-regulator as it duplicates with
tps65090-pmic for regulator driver.

Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>