Delete ufshcd_read_power_desc() and ufshcd_read_device_desc(), directly
inline ufshcd_read_desc() into its callers.

Link: https://lore.kernel.org/r/20200120130820.1737-6-huobean@gmail.comReviewed-by: NAlim Akhtar <alim.akhtar@samsung.com>
Reviewed-by: NAsutosh Das <asutoshd@codeaurora.org>
Signed-off-by: NBean Huo <beanhuo@micron.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>