phy: exynos5-usbdrd: Remove "static" from local variable

The 'reg' local variable does not need to be static.

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Reviewed-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>