At UFS initialization stage, to get the length of the descriptor,
ufshcd_read_desc_length() was being called 6 times. Instead, we will
capture the descriptor size the first time we'll read it.

Delete unnecessary redundant code, remove ufshcd_read_desc_length(),
ufshcd_init_desc_sizes(), and boost UFS initialization.

Link: https://lore.kernel.org/r/20200603091959.27618-5-huobean@gmail.comAcked-by: Avri Altman <avri.altman@wdc.com>
Reviewed-by: Bart van Assche <bvanassche@acm.org>
Reviewed-by: Stanley Chu <stanley.chu@mediatek.com>
Signed-off-by: Bean Huo <beanhuo@micron.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>