scsi: ufs: Move ufshcd_get_max_pwr_mode() to ufshcd_device_params_init()

ufshcd_get_max_pwr_mode() only need to be called once while booting, take
it out from ufshcd_probe_hba() and inline into ufshcd_device_params_init().

Link: https://lore.kernel.org/r/20200120130820.1737-5-huobean@gmail.com
Reviewed-by: Stanley Chu <stanley.chu@mediatek.com>
Reviewed-by: Asutosh Das <asutoshd@codeaurora.org>
Signed-off-by: Bean Huo <beanhuo@micron.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
