mfd: Return proper error if tps65090 regmap_init_i2c fails

Return proper error instead of 0 if regmap_init_i2c fails.

Signed-off-by: Axel Lin <axel.lin@gmail.com>
Acked-by: Venu Byravarasu <vbyravarasu@nvidia.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>