dm816x_usb_phy_init() sets variable 'error' but never uses it, so remove
it.

drivers/phy/ti/phy-dm816x-usb.c:85:6: warning: variable ‘error’ set but
not used [-Wunused-but-set-variable]

Link: https://lore.kernel.org/r/20200629145010.122675-3-vkoul@kernel.orgSigned-off-by: Vinod Koul <vkoul@kernel.org>