USB: Handle -EPROBE_DEFER with clk_get() API usage

Linux clock driver is moving with device tree usage. With that it
is not necessary that before USB/HSIC/OTG driver probe called,
clock driver would be initialized and would be able to provide
required clk related operations. In this condition, -EPROBE_DEFER
is returned by clock driver. Handle this condition and move all
clk_get() usage with initial part of probe() to avoid multiple
time resource initialization and de-initialization with it.

CRs-Fixed: 524795
Change-Id: Ie9176c1f50ceefabd2ddb1961446db37d8c24bdc
Signed-off-by: Mayank Rana <mrana@codeaurora.org>