usb: dwc3: exynos: Fix error handling of clk_prepare_enable

If clk_prepare_enable() fails in dwc3_exynos_probe() or in
dwc3_exynos_resume(), exynos->clks[0] is left undisabled
because of usage preincrement in while condition.

Found by Linux Driver Verification project (linuxtesting.org).

Fixes: 9f216836 ("usb: dwc3: exynos: Rework clock handling and prepare for new variants")
Acked-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>