phy: qcom-ufs: Don't return error if fail to get optional resource

phy: qcom-ufs: Don't return error if fail to get optional resource

"dev_ref_clk_ctrl_mem" is optional resource, so don't return error if fail to
get the resource. Since it's an optional resource, don't emit error if
fail to get dev_ref_clk_ctrl_mem.

Also remove redundant test for res, it's done by devm_ioremap_resource().

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>